Rob Galbraith DPI notes:
"Canon has released firmware updates for the EOS-1D Mark II, EOS-1Ds Mark II and EOS-1D Mark II N that enable these camera models to properly recognize the capacity of CompactFlash cards larger than 8GB (such as SanDisk's Extreme III 12GB and 16GB), as well as accept SD cards that adhere to the SDHC specification."