While these location-sharing services have some interesting possibilities, they also raise some disturbing implications for privacy — or maybe it just seems that way if, like me, you’re over 35 years old. Lately I’ve been testing a cellphone location-sharing service that I found simple, useful and non-creepy enough that I can imagine people thirtysomething and older using it.

Send a ‘Glympse’ to share your location

The free service is called Glympse, from a company of the same name that has designed it to share your location with friends and colleagues in small increments of time — glimpses, as the name implies, of your whereabouts. Glympse just released a test version of the service as an application for the G1, a phone offered by T-Mobile that runs Google’s (GOOG) Android operating system.

The company will release versions of Glympse for BlackBerry, Windows Mobile, iPhone and Nokia (NOK) phones in the coming weeks. Users can download the Glympse software onto G1 phones through Android Market, the online clearinghouse for applications for Android phones.

I used Glympse on an iPhone and a G1 and, for comparison, tried out a couple of other location-sharing applications, Google Latitude and Loopt. When you start the Glympse application, it identifies where you are on a map using a combination of location technologies in cellphones, including GPS satellites, Wi-Fi hot spots and phone towers.

Your location isn’t shared with others until you “send a Glympse” to someone. The software allowed me to send a Glympse with my location for selected chunks of time lasting anywhere from zero minutes to four hours. Picking zero minutes shared only my location at the moment of sending, while selecting four hours meant the recipients of my Glympse could track me for that period of time, wherever I went.

The sender of a Glympse can address it by entering a recipient’s email address, or a mobile-phone number for a text message. Recipients get a message with a link to a map on a Web page. A nice thing about the service is that it doesn’t require recipients to have the Glympse software, though the experience is richer when they do.

Sending a Glympse can be helpful anytime a friend, family member or colleague is expecting you. You can send a Glympse that lets a friend know you’re stuck in heavy traffic (although it’s wise to do that before you’re on the road to stay safe and, in some states, to avoid breaking the law). Parents can insist that teens send a Glympse when they go out for the evening.

Bryan Trussel, the CEO of Glympse, sent me several Glympses with short messages like “late lunch meeting” and “headed home” to explain where he was going. On the G1, I could see an icon representing Mr. Trussel moving around a map as he drove through the streets of Redmond, Wash., including his speed. I was also able to see traffic conditions, which would have been helpful if he had been running late. Glympse gave me a similar view of his location through a Web browser running on my PC. On the iPhone, the experience was more static, forcing me to reload a Web page to get a fresh view of Mr. Trussel’s whereabouts. Glympse says it will fix this so users of the iPhone can watch someone’s location in real time.

I encountered a bug with the service when I sent a couple Glympses to my own cellphone and that of a colleague — both BlackBerrys and neither of which had Glympse software. Both Glympses linked to high-level maps suggesting I was somewhere in North America, which wasn’t very helpful, even if it was technically accurate. The company couldn’t figure out what the problem was, and it eventually stopped happening for me too.

Once a Glympse expires, the service no longer tracks the sender’s location. It will show the sender’s last known location for 48 hours after the Glympse expires. Glympse may some day use your location information to target advertising to you, but the company isn’t doing that for now.

I’m far more comfortable with this form of finite location-sharing than the approach used by other services. Google Latitude lets you share your location to only a list of friends. It gives you the option of turning location sharing off or, through a “city level” option, it reveals only your general whereabouts. Loopt similarly allows you to set options to show, or hide your location from all or some online friends. A feature called Loopt Mix lists strangers you can send messages to in your general vicinity — many of whom seemed to be looking for romantic partners in my area.

Despite these controls, I easily forgot I was sharing my location with these two services. This might be fine for someone who enjoys being tracked down by friends during a night out on the town or is diligent about changing privacy settings when they want to go stealth.

I’m too lazy to manage my privacy so closely though. I don’t mind giving friends a look at my location, but only if I know the invitation isn’t open-ended.

• Email nick.wingfield@wsj.com.

This contrast has appeared sharper in recent years, as Microsoft’s Windows Vista operating system received a tepid critical response compared with Apple’s Leopard platform and as the company’s Live Web search service has slipped further behind Google’s. In addition, Microsoft’s cellphone software, Windows Mobile, looks old and creaky compared with Apple’s sleek iPhone and Google’s forthcoming Android mobile operating system.

But innovation does exist at Microsoft’s sprawling Redmond, Wash., campus. For instance, last year’s daring and radical redesign of Microsoft Office has been a critical and commercial success.

Now, there’s a sort of guerrilla team inside Microsoft designed to churn out innovative products more often and more rapidly. Called Live Labs, the unit is a small operation that aims to turn technology theories into real, Web-based products relatively quickly. It has only about 125 employees, and even that modest number is broken up into smaller teams tackling specific projects.

This week, Microsoft Live Labs is releasing its first broad consumer Web service, called Photosynth. This service turns multiple photos of a scene or site — say, an art gallery or a building — into a 3-D scene you can virtually “walk” through on the Web.

Unlike a simple 2-D panorama, which many photo programs can create from several pictures, a Photosynth creation, called a “synth,” is a virtual 3-D environment. It gives you the feeling you are in the middle of a room looking around, or circumnavigating a building or object. You can travel through a scene both laterally and vertically, and zoom in to see detailed, higher-resolution views of objects inside the synth, such as paintings on a wall.

For instance, you don’t just see a long, flat picture of Stonehenge or the Grand Canal in Venice. You are made to feel you are there, moving through these places, looking up at the sky or down at the ground, and pausing to examine more closely a particular stone, boat or building.

Such 3-D walk-through images have been around for awhile; they are used on some real-estate Web sites, for example, to show houses virtually. But Photosynth allows anyone to create them using any standard digital camera, and even using pictures you already possess that weren’t created with Photosynth in mind. You could even use photos of the same site taken by several people. The software will analyze the pictures, figure out which ones overlap and in what order, and then turn those shots that match up into a 3-D synth.

Photosynth, based on technology Microsoft acquired in 2006, is entirely free, and it’s entirely based on the Web, at photosynth.net (where it will be launched at midnight EST Thursday). At that site you can view not only your own synths, but the synths created by every other Photosynth user.

I’ve been testing this service for about a week, and while it has its flaws, I believe that Photosynth offers a dramatic new way to use your photos and to share them with others.

Photosynth works within a Web browser, using a small plug-in you install. Currently, it works only in Windows, using Microsoft’s own Internet Explorer browser or its rival, Firefox. A Macintosh version is in the works, but for now, you can’t even view others’ synths in the Mac operating system.

When Photosynth works right, the results are wonderfully satisfying. But it takes some skill to get a set of photos the service can match up well, a quality Microsoft calls being “synthy.” Ideally, portions of each slice of a 3-D scene should show up in at least three photos, with 50% overlap between them. After you upload your pictures and Photosynth does its best to make them into a 3-D scene, the service assigns them a percentage number that indicates how synthy they were.

In my tests, I tried both collections of photos I already possessed and some I snapped with Photosynth in mind. My pictures of a piazza in Verona, Italy, were only 38% synthy, while ones I took of a hotel room specifically for Photosynth use were 73% synthy.

One gripe I had was that Photosynth doesn’t tell you how synthy your pictures are until after you have uploaded them and waited until the system merges them, a process that can take a long time over a slow Internet connection. It would be much better if the service could tell you in advance how synthy the pictures are. Another objection is that Photosynth has no privacy settings. All your synths are open to viewing by everyone who uses the service.

But, overall, Photosynth is an impressive new way to view and share photos, and an encouraging sign that innovation and creativity still live in Redmond.

Find all of Walt Mossberg’s columns and videos online, free, at the All Things Digital Web site, walt.allthingsd.com. Email him at mossberg@wsj.com.