Rumsfeld of course should go, and it's really somewhat surprising that aside from Bill Kristol there haven't been many on the Right who have echoed this line.
After the whole Blackhawk Down affair the calls to oust Les Aspin were pretty incessant.
But, let's not kid ourselves and imagine replacing Rumsfeld will achieve much. Bush is unlikely to let anyone come aboard who will puncture his little fantasy bubble. The policy will stay the same - we stay in Iraq, because leaving=losing in Bushworld.
...Bush released statement just now: Rumsfeld has his full support and is "exactly what is needed an this critical period."