Yes i am! I started using foursquare on 12th June 2010. That was when i first unlocked the Newbie badge. At first it was fun to check in to different places bcoz my friends in fb and twitter would know my where abouts since i set it to post my locations to fb and twitter. Then it became more fun after i found out there are a lot of badges to unlock and i became obsessed with unlocking the cute little badges. The new fb for blackberry also has the function where you can check in to places yo go but it's no fun bcoz it doesn't unlock badges like foursquare. My sister was quite worried with me using foursquare at first bcoz she said one of her colleague's friend's house was broken into all bcoz of foursquare. Well, sorry to say but some people are really stupid to check in to their homes on foursquare, revealing their full address. And some people don't know that they can still check in without posting the location to fb or twitter. Now that my sister also has a blackberry, she's hooked on foursquare too. Haha
I've just learned a few tricks on how to unlock foursquare badges (no i'm not going to share it). Hehehe. So nowadays i mostly check in to places which i know i can unlock new badges and i only post my locations to twitter instead of fb. I now have 36 badges and still counting. Some may say it's a waste of time but for me, it's a hobby that doesn't cost a single cent.