Canon has announced a firmware update for the EOS 5D Mark III camera and has made the firmware version 1.3.3. available for download

This firmware update improves the AF controllability when shooting in the Live view mode using a wide angle lens (either fixed focal or zoom lens)

and corrects some inaccuracies in the English and Russian menu screens.

This upgrade is for cameras with firmware versions 1.2.3 or earlier. Please read the download instructions in the Canon site linked above before updating. Always remember to have sufficient charge in your battery.