Yeah, funny, I was thinking of a similar principle. However, mine is slightly different. You match people using collaborative filtering techniques based on your social network profile (bayesian filtering, for example. . .). Then you via gps on your cell phone. IE, if two likely matches happen to be geographically close to each other, the cell phone tells both of you "hey, you guys would be a good match . . . would you like to hook up at a nearby coffee place?". If both say yes, the cell phone will allow you to meet at a local coffee place (or whatever).

The point is is to have a weird excuse to interact briefly. Just by a brief encounter one can know if that person is his/her type.