I have just updated my camera to the latest version of the firmware available from Canon (as of yesterday).
Its version 1.1.0 and the main improvements are in the movie mode, basicaly you now have control over asa, aperture and shutter speed.
This was a much requested feature (the camera was auto everything before this – with no easy way to control any variable).
Previously the popular way to control aperture in movie mode was to use Nikon lenses on an adapter, this may have been noticed by Canon…..
If you do shoot short movie clips when on location (a good idea) then consider the upgrade, if not then read about the changes first then decide if you want to update, you can read and download from here:
http://web.canon.jp/imaging/eosd/firm-e/eos5dmk2/firmware.html