The firmware upgrade for the Sony A7 & A7r is now available. You can download the update here. Be sure to download the correct one for the correct camera and operating system.
Sony A7 & A7r Improvements
I'm seeing people reporting few improvements. Mainly faster boot times and faster autofocus. Sony claims there is an improvement to the image quality. Only thing I've seen from users at this point is a slight improvement at higher ISO's. Still waiting on someone to do a full deep and dirty nerd test on it.
Note: I've seen a lot of people saying the firmware bricked their A7r when applied from OSx. To unbrick their camera they had to reapply the firmware on a PC. So I recommend updating your firmware on a PC if you can.
I've yet to update mine. But will do it very soon.