One of the odd aspects of the Facebook event launching the new Facebook Places service was the participation, support, and partnership of competing location-based check-in services.
Foursquare - News, Features, and Slideshows
Suddenly, there are two kinds of people. The first kind loves location-based social networking services like Foursquare. They speak in an alien language about "Mayors" and "Badges" and broadcast their locations to the world.