Cheating spouses, drug dealers and truant teenagers beware.

If you’ve updated your iPhone Facebook app in the past few days, you may have noticed a glowing halo surrounding a new icon, smack dab in the center of your app home screen. I snagged a screenshot of mine before it disappeared into the permanence of mobile Facebook-dom.

Facebook Places welcome screen after updating the iPhone Facebook application.

Okay, fear-mongering aside, we’ve been here before. Facebook rolls out a new service, the ACLU enjoys the public outcry over privacy issues, and after a few weeks, the masses latch onto the new service. And they like it. Dissenters finally figure out how to tweak the updated privacy settings, high schoolers spam the new service with inside jokes, and life goes on. A notable person here or there deletes his or her Facebook account on principle.

But this time, the stakes truly have been raised. On Wednesday, Facebook launched “Places,” a geolocation service that allows you to “check in” from wherever you are. It goes without saying that you can also geo-tag any of your friends, publicly broadcasting their whereabouts. 

Facebook was sly and cool about the release, so in case you missed the boat, here’s a timeline of events:

WEDNESDAY: Facebook launches Places with as much hoopla as a press conference and blog post. 

THURSDAY: Google Mobile Blog posts a reminder of how awesome Google Maps is, just in case you forgot.

THURSDAY EVENING: Foursquare co-founder and CEO Dennis Crowley announces the “biggest day ever” in terms of the geolocation service’s new signups, nearing their total user base to 3 million. (Facebook has 500 million users, to put this in context.)

FRIDAY: Most Facebook users still have no idea what Facebook Places (or geolocation, for that matter) is. The most common response is: “huh?”

FRIDAY EVENING: In response to criticism over fishy privacy issues (as always) and confusing opt-in/opt-out results, Facebook releases a step-by-step instructional video for the new service.

NEXT WEEK: Despite some ruffled feathers over being unintentionally “checked in” by an annoying friend or two, the buzz catches on. 

IN TWO WEEKS: And just like untagging yourself in photos from a party that hosted a bathtub full of jungle juice, those who want to hide, do. Those who don’t will check in at every store and swanky coffee shop they pass on foot. The dust settles.

Okay, I turned on the flux capacitor a bit for this one, but the trajectory is common. Someone comes up with a hot new service that a small niche of the population really digs (e.g. Foursquare). Facebook slides in, stealthily distributes the trend to its hundreds of millions of users and slaps on the brand of standardization. 

This technology isn’t new. As noted, Foursquare already has nearly 3 million users, and Google Maps has been using location-based mobile networking with 100 million users since it launched nearly five years ago. Facebook, however, is opening the technology to its existing (and growing) user base of 500 million, 150 million of whom already sign in with their mobile phones.

Geolocation, however, is the closest social networking has ever come to actually being social. TechCrunch’s MG Siegler pointed out in 2009 that social networks have always lacked the actual in-person “social” element. Geolocation-based networks may be the answer. Text messaging the person sitting next to you doesn’t even come close. However, “checking in” at the mall and using your Facebook app to find friends before you actually run into them is a whole different ball game. Here’s your chance to avoid an awkward encounter with your ex. Or to make one happen, to his or her delight.

But it would be naïve to put the blinders on and shove aside skepticism entirely. Sure, most people will use this technology in a positive way, to facilitate face-to-face social interaction. However, the ability of laypeople to locate, track and publicize their neighbors’ whereabouts lends a great deal of power to the people. And power, as it’s been said, corrupts.

It’s not Facebook who’s outing us, publicly tagging personal details and controlling the information highway. Our friends are.

For the first time in history, we’re actually moving toward a system where the societal behemoths (read: Facebook and Google) aren’t telling us what to do or where to go. They want us to do that ourselves. Do we trust ourselves?

Jump forward a generation or two. What would a self-policing society look like? Third-party direct marketing may become obsolete. We’d know all of our favorite brands and labels from each other. Instant access to any person at any place in the world at any time of day may become the norm. We’d no longer need to schedule so many meetings. Privacy issues may become a thing of the past. We’d laugh at how silly we were to get so heated about protecting our information from others. How did we used to function without sharing everything, always?!

No one can predict how social media will continue to shift our "real" social interactions, but it’s important to stay on our toes. Geolocation technology is already leveling the playing field—quite literally—with hundreds of millions of people all over the world. If you’re reading this post, you’re probably already a part of it.

For now, the social networking evolution continues to ebb and flow in different areas, with lots of buzz about privacy, net neutrality and other timely Web issues. But with the exponential rate of tech advancement, we’d be amiss to not step back and take a longer view of where we could eventually land. A check-in from the future would be useful.

Facebook may revolutionize social media (again) with Places, or the new service may totally creep out this generation, relinquishing it to simply another notch on the social media ladder. Regardless, geolocation technology is here to stay. Only time will tell how it will eventually be used.

But for now, one thing’s for sure. Stalking people has never been easier.

Reach columnist Lisa Rau here.

Follow her on Twitter: @LisaRau