This release has been renamed iOS 6.1.3.
iOS 6.1.3 Beta 2 includes a security fix for a Lock screen bug and the following improvements to Maps for Japan:
● Improved pronunciation of roads during turn-by-turn navigation
● Optimized directions to more strongly prefer highways over narrower roads
● Now indicates upcoming toll roads during turn-by-turn navigation
● Added labels for junctions, interchanges, on-ramps, off-ramps, and intersections
● Added indicators for transit station buildings, subway lines, and traffic lights
● Updated freeway color to green
● Updated icons for some location categories including fire stations, hospitals, and post offices
● Added 3D buildings including Tokyo Station, Japan Imperial Palace, and Tokyo Tower
You can get the new build (10B318) from the iOS Dev Center.