One of the best ways to send HD material between devices is 1394, for one it has tons of bandwidth, it is very versatile and has good industry support. We are not sure why it isn't included in more TVs especially considering that so many TVs include ATSC tuners. We don't subscribe to the evil MPAA theory, but we don't have a better explanation either.
Either way we are glad to have the new faster version included in Vista, not because we need the extra throughput, but because of the distance that 1394 over CAT5 gives us. 1394b combined with a network technology like HANA has alot of promise and OS support is the first of many pieces that must come together to give us the whole home media nirvana that we all dream of, now we just need 5C support.