Huge blow to the Gowalla and Foursquare camps.

Yelp has boatloads of venues already, they obviously have an even larger number of legit and useful reviews, and they most importantly have existing relationships with these businesses (at least on the order of Yelp window stickers). Soon to come, deals for having a Regular badge at a given bar, or special happy-hour specials if you check in with multiple friends.

I’m a huge Gowalla fan, but these updates leave only one feature necessary for the Yelp app to really put the future of both Gowalla and Foursquare in jeopardy: contact import from facebook/twitter/etc. At that point, Gowalla will look like a “not as powerful, more game-like” version of Yelp’s offering.