The official Canon announcement is here...
Vincent Laforet who immortalised the Canon 5D MkII has done a sneak preview yet again. And written a stirring piece on the future of HD-DSLRs here
And the movie he shot is available in full HD glory at smugmug here
Meanwhile, fxguide.com reports that the 5DMkII will soon have 24fps and 25fps capability in the months to come. With the coming of the 7D that does 24 and 25fps, and now the 1DMkIV, that will also do 24 and 25 fps. Canon probably realised that there would be a drop in 5D MkII sales (which only does 30fps), hence this addition.
Vincent's view on HD-DSLRs is apt, and I too see this as a paradigm shift to cameras that shoot with little or no light. But it needs cinematographers who see shooting movies that way. Or, there could be a breed of new photographers turned cinematographers, and docu film-makers who will do things different.
HD-DSLR video also mean doing movies that need little or no colour grading after shooting. This is also a big deal in these days of 'safety film' - meaning a medium with lots of latitude - which is what film is viewed as. Canon HD movies don't have that kind of latitude so you pretty much have to 'make do' with what you shoot.