No firewire 800 is most likely because iMacs (and iBooks and eMacs) are targeted at consumers (and maybe a little at 'prosumers') and not at proffessionals. A big part of their appeal is simplicity, and having 2 different firewire ports is not simple for the average consumer. Also, these people are buying Macs to make home movies w/ firewire400 cameras, and they may buy some firewire 400 devices, but it is not worth it to them to invest in very new, very expensive firewire800 devices. They don't need 800, they most likely won't use it, and Apple (IMHO) needs more actual features (not just potential features, like expandability/upgradeability) that separate the pro machines form the consumer machines.