Who has played a game of Dietbet?

I seem to keep reading articles about how social media is changing to help people become more goal oriented (that's why we're all here at MFP, but they were referring to closed-ended challenges). I found Dietbet, where you can join a game that lasts 28 days and your goal is to lose 4% of your body weight (for me that's 7 lb.). So far I find it REALLY motivating because it's only 28 days. I can do 28 days! All the long-term, 90-day or 30# type goals just seem so darn overwhelming, but I like this. It'll cost you something to join a game - it varies from $20 - $40, totally up to you -- and if you reach the goal you get your money back plus a share from all those who didn't make the goal. What a genius idea.

Check it out. http://www.dietbet.com/

Incidentally, I'm 7 days in and have lost 4.1 lb. We know some of that was water, but STILL. I'm feelin' good.