I agree with Yglesias that the recent Republican attacks on Obama for being a "flip flopper" and moving to the right will likely count as one of the biggest own-goals in the history of American politics. The centre (or "center") is where it's at. McCain could have won this thing on one strategy alone: he's in the middle (not like those other R's) and Obama is a crazy radical with nice speeches.
If Obama is a normal politician who will pander however he needs to, then the median American voter will be relieved. It's time to give the Dems a try. It might be interesting to have a black guy who writes books. McCain's old. But that same median voter has (reasonably enough) some lurking suspicions about this dude. McCain and the Republicans telling you he is just an opportunistic office-seeker like all the others will just reassure those suspicions.
And could we end the "Rove proved that you don't need the centre" crap. First, that is not really how either 2000 or 2004 worked. Second, to the extent that Rove tried a mobilize-the-base strategy, how did that work out for the GOP? One voter switching in the middle is worth two on the edges deciding not to vote or vote for a third party, and there are more voters in the middle.