This is a brief diary, but I just saw the posting on Politico - Mitch Daniels is not going to run. The reason given is his wife's concern. I can think of a few other possibilities of course - his problems with the wingnuts. He's not crazy enough for them, and he has Syrian heritage.
This takes one of the "serious" candidates off the list, and leaves Romney, Huntsman, and Pawlenty on the "serious" list. All have big problems with their base. I certainly don't want to be complacent, but this is going to be a very entertaining Republican primary season.
Updated with Link, thanks to virginwoolf for reminding me.