According to FixMy5D, the Canon 5D Mark II was launched prematurely:
I've just received insider information from Canon. Someone I know, who had to make a video clip for a well known music star in Switzerland, spoke to a higher-up from Canon.
They told him that the release of the 5D Mark II was actually not planned for October but rather for Sping 2009. But since Nikon released a video DSLR (D90) they were forced to also release one.
Originally full manual control was planned but they couldn't finish it by the time of the release.
This of course explaines also the low suply from Canon.
Well if this is true we have a good chance to see a firmware update soon.
Source: FixMy5D on 3/5/2009.