There is, without a shadow of a doubt, something profoundly disconcerting about FourSquare.

It’s not even the Web service’s fault; it’s a perfectly nice piece of software. It’s more what it does – encourage users to pinpoint themselves on a map, in real time, as often as they can. It’s like Twitter, but for locations. Instead of asking the question, “What are you thinking?” FourSquare asks, “Where are you right now?” It uses your smart phone’s GPS locator to answer – and then it tells all your friends. Why? Because it’s 2009, and that’s the kind of thing we do nowadays.

FourSquare is already making waves with the early adopter crowd. It remains to be seen whether this particular service will catch on, but something like it undoubtedly will. GPS is a standard feature on smart phones now, and people seem to have acquired a taste for disclosure. Compulsive thought-sharing is about to be joined by compulsive location-sharing.

But before you start eyeballing your phone with new loathing, just remember: It’s not about surveillance or tracking or oversharing – it’s about ego. FourSquare is both an application and a website. Just like every other social network, you build a “friends” list of people you may or may not actually like. When you decide to “check in,” or publicly announce your location, FourSquare uses your phone’s GPS to get your co-ordinates, then cross-checks them against its mighty database of locations.

That way, it doesn’t just put you on a map, it names the specific office, school, restaurant, plaza, bar, tea shop, coffee shop, hemp shop, tackle shop or vaccination lineup you happen to be in. (If that location isn’t in the database, FourSquare offers to let you add it yourself. It also features a gimmicky scoring system that promises to reward frequent users with real-world discounts, though I’ve found it more irksome than anything else.)

Truth be told, it is fascinating to see where your friends have been in the past day or over the past week. It uncovers patterns about their daily lives that you might not have recognized; it uncovers tastes you might not have known they had. Sometimes it takes a computer pointing out that your friend shows up at a downtown theatre every week to unearth the fact that he’s enrolled in avant-garde yodelling classes. It could also be handy: A public “check-in” can serve as an open invitation, a beacon that friends can home in on without needing to be individually asked.

But really, wondering about the practicality of a new social networking tool is like questioning the artistic merits of a new reality show: It’s not the point. At the outset, even Twitter’s own founders didn’t know exactly what it was useful for. They just knew people were getting a kick out of it, so figured it must be worthwhile. And at the end of the day, just like Twitter and Facebook, FourSquare simply represents another way of inviting semi-strangers to share your life and performing for them.

After all, the simple act of being someplace is a form of self-expression. Where you’ve been says as much about you as what you wear, or what music you’re listening to or what’s on your mind. It’s a piece of the puzzle of identity; it’s the hot iron of personal branding, hovering auspiciously above your hindquarters.

Since FourSquare lets you choose when to locate yourself, you can be sure that users will put themselves on the map with an eye toward reinforcing their self-image. Would you rather your contacts perceive you as a club-goer or a homebody? Would you like to come off as a compulsive library-goer or food shopper? McDonald’s or Gary’s Falafel Palace? Sears or Mark’s Work Wearhouse?

Some pitfalls are easy to spot. Safety is one of them. Although FourSquare broadcasts users’ locations only when they decide to check in, it can make some of their routines predictable. If you notice that a person checks in at a given school every Thursday night at 8, it’s a good bet you’ll know where to find them week after week.

It seems inevitable that, at some point, this will be abused. Someone, somewhere, will suffer an assault after broadcasting their location. The technology will be impugned, whether or not it bears any meaningful connection to the crime. There will be a well-publicized horror story or two. Followed by a whole new safety panic, especially where kids are involved.

These concerns aren’t without merit, but we’ve been here before. People will have to learn how to use FourSquare and its ilk wisely, just as we’ve all learned what things Facebook shouldn’t be used for. It’s easy to fret about the potential for FourSquare to lure the unsuspecting into needless and catastrophic overexposure. But it’s important to remember that, at its core, it’s not a tool for tracking people down. It’s a tool for showing off the places you’ve been, and that’s a tool for showing off the kind of person you are. I suppose you could rely on thoughts, words and deeds instead, but that would be an awful waste of an iPhone.