I just bought one of these as a backup/really-foul-weater camera to my A7S since I had heard XAVC-S was coming in a flash update (because it already has the new BionzX processor.) Lo and behold, Sony has delivered. Makes this camera a good choice for low-cost, weather-resistant run-and-gun now.

This new firmware update (2.0) brings faster focusing and adds XAVC-S 50/mbps HD video to the A77II DSLT camera. (NOT THE A7II, which already has XAVC-S and ships later this week.)

China Download (universal binary, works perfectly on US Cameras... I updated mine no problem.)
SONY China Service-ILCA-77M2 ?????????????Ver.2.00? Windows (http://service.sony.com.cn/DI/Download/67508.htm)

Update: Now available on American site
http://esupport.sony.com/US/p/model-home.pl?mdl=ILCA77M2&template_id=1&region_id=1&tab=download#/downloadTab

US Firmware Update (not live yet.)
Sony eSupport - ILCA-77M2 - Support (http://esupport.sony.com/US/p/model-home.pl?mdl=ILCA77M2&template_id=1&region_id=1&tab=download#/downloadTab)

SAR lists other firmware pages, if you can't find yours:
Sony China already lists the (super!) new A77II firmware update! | sonyalpharumors (http://www.sonyalpharumors.com/sony-china-already-lists-the-super-new-a77ii-firmware-update/)