As expected in anticipation of the new 580EX flash unit, Canon has posted a firmware update for the 1D Mark II. According to the Canon site this update:This firmware update fixes/improves the following:
Added new functions for communicating with the Speedlite 580EX.
A color temperature information transmission function has been added to stabilize the white balance.
Reduced noise when shooting bulb exposures.
Reduced the noise when shooting bulb exposures (astronomical shots, etc.).
Fixed sensor-cleaning operations.
Fixed the problem of the shutter not opening if sensor cleaning was performed immediately after taking bulb exposures.
You can download the update from this Canon support page (http://www.canon.co.jp/Imaging/eos1dm2/eos1dmk2_firmware-e.html).