In addition to pushing iOS 6.0.1 to users earlier today, Apple has just pushed the first beta of iOS 6.1 for the iPhone 3GS, iPhone 4, iPhone 4S, iPhone 5, iPad 2, third- and fourth-gen iPads, and fourth- and fifth-gen iPod touch to registered developers. Curiously, however, it does not yet seem to be available for the iPad mini.
Source: developer.apple.com