SXSW is no stranger to having themes tied to the event. This year was undeniably mobile services, more specifically, services dedicated to your location and allowing you to share that location with other people to create friends and events on the spot.
Although the two big dogs in the mobile location world, Gowalla and Foursquare are still vying for your attention, many other services have launched or are getting ready to launch. While the check-in systems are slightly different from one another in the two main services, both boasted huge numbers at SXSW.
Probably the most interesting service to arise at SXSW was Check.in which will update and check you in to all of the major services at once. I suppose it is going to be something like Ping.fm except for location services. Sounds pretty neat to me.