I'm a heavy FourSquare user and am intrigued by Location Based Services at large. LBS related stuff will lead to the most significant behavioral changes on Earth since the network came online 15
The fact it took BrightKite and Loopt as long as it did to distribute their iPhone apps must be some indication as to how niche the market continues to be. That's a bummer
If you don't want to see a grown man gush like a tween at a Britney Spears concert, stop reading. I've been a sucker for the pairing of lat/lng based data/apps