A Vodafone branded Nokia Lumia 800 ROM leaked yesterday. The exact firmware version of this is 1600.2487.8107.1207. Now, the good guys/gals at XDA Developers have given it a spin, and concluded that it will bring the following changes:
Battery drain issue has been fixed
Lack of audio Bass when listening through headsets has been addressed
Auto-white balance issue with the camera has been fixed
Hardware buttons backlights are now always illuminated at all available screen brightness levels
Diagnostics app has been updated to prevent users from receiving misleading technical readouts about their device
Great! It sounds like this would fix every problem related to the Lumia 800.
The update should be right around the corner, so stay tuned for more new on when it is actually available!