updated 01:06 pm EDT, Tue March 19, 2013
Japanese users get additional Maps improvements
(Updated with Apple TV 5.2.1 info) Apple has released the final version of iOS 6.1.3 to the public as an over-the-air update, with an iTunes distribution likely to arrive later today. The firmware is a minor update, mainly solving a lockscreen bypass made possible via a glitch in the iPhone's Emergency Call function. When used, the bypass would give people access to private data like contacts and voicemail messages.
6.1.3 is also said to make "improvements to Maps in Japan," but Apple doesn't go into any further detail in its release notes. The company in fact pushed out some Maps improvements to Japanese users without an iOS update, so it's unclear what may have already been added and what's new.
Update: A v5.2.1 update has been released for the Apple TV, but any changes beyond a handful of security fixes have yet to be discovered.