Just to take your HCI point - 1 second is too long yes, but instant switching is too short. Fine for power users yes, but for the majority of people there needs to be a slight delay. this is true accross the board for computing - extending to consoles where with some Nintendo64 games developers artificially put a few seconds of 'loading' time in because users were put off by the almost instantaneous loading.
No one is saying that Vista is the be all end all, just that it is going to be a big change for microsoft - which certainly looks to be the case.