Bush says that he takes responsibility for failures in dealing with Katrina. I didn't think that he had it in him -- he didn't acknowledge his tax cuts had anything to do with the deficit, didn't hold anyone of significance accountable for killing and abusing prisoners in Iraq, and didn't hold anyone (period) accountable for the WMD intelligence failures which led to the war. Now for once he's acted like the "MBA President" we were all told to expect: he's fired and replaced his worthless friend to whom he gave the FEMA job, he's said "I am responsible," and he seems to be committed to giving the situation the attention that it deserves. Good.
Unfortunately, his acceptance of responsibility wasn't unqualified; His statement was actually "to the extent the federal government didn't fully do its job right, I take responsibility." This leaves room for the possibility that the federal government did do its job right, which I think is generally agreed to be ridiculous.
Still, you can't ask someone to change five years of bad habits overnight... it's a step in the right direction.