Taste Neighbors (continued)

A few summers ago, I penned a post called Taste Neighbors in which I described a web service that would do for food/restaurants what last.fm has done for music. From that post:

This problem has largely been solved in music. Because its relatively simple to watch what music I listen to and what music millions of others listen to, there are many services now that use musical neighbors to drive recommendations. My personal favorite of these services is last.fm and this is a list of my musical neighbors.

and

I am more optimistic about watching what they actually do. As my former partner Bliss used to say, "watch what they do, not what they say". With online finance services like Wesabe (one of our portfolio companies), you can easily build a database of every restaurant you eat at, every movie you go out and see, every book you buy from Amazon, etc.

Well Wesabe has come and gone but my interest in a taste neighbors service has not.

Last night my friend Vanessa said to a few of us, "couldn't you look at my foursquare checkins and figure out what other foursquare users like to go to the same places I like to go and then using their checkin history, recommend other places I might like to go?"

Bingo.

So is anyone doing this? Can it be done via the existing Foursquare API? I think this is a big idea and I'd like to see some people working on it.