It looks like the new LG G Watch and Samsung Gear Live are already getting their first update. The KMV78V update started pushing out OTA to the two Android Wear devices today. Users should start seeing the update within the next few days as it rolls out in waves.
At present there's no official changelog out there to give us a hint what this update addresses. For the most part we suspect last minute bug fixes and performance improvements. The update will hit your device via its Bluetooth connection to your phone. Sound off when you get this update and let us know if you notice anything different.
Here's our dedicated Android Wear section: http://www.droidforums.net/forums/android-watches.652/