updated 01:42 pm EST, Thu February 21, 2013
First beta was actually 6.1.1
Apple is seeding iOS 6.1.3 beta 2 to developers. The first beta was originally released under the v6.1.1 header, but Apple quickly turned that version around to solve problems with 3G access on the iPhone 4S. The v6.1.2 update quashed an Exchange bug.
Notes for v6.1.3 say that it eliminates the lockscreen bypass vulnerability in v6.1, and includes previously-promised upgrades to the Japanese edition of Maps. Among those are navigation tweaks, new labeling, and a collection of added 3D objects.