In a first for US mobile carriers, Sprint has opened up an initial set of REST services for developers to play with for free at their new developer sandbox. With these services (Sprint API profile), developers can now access location, simple presence, and send SMS messages to Sprint handsets without requiring any software installed to the device.
It's a little bit creepy, but it's also a little bit genius. Singles for Foursquare builds a dating and messaging service on top of the location-sharing application. The result is a mashup that could match up hip iPhone-using, Foursquare-playing, same-bar-going early adopters.