never been the biggest Paul Krugman fan... too much of a political cheerleader and often prioritizes political points over good economics, doesn't listen to critiques of his work, assaults other high-profile economists on topics they've done a lot more work on, etc. Generally, just disagree with him on a lot.
Krugman called Mankiw an idiot, basically, because Mankiw didn't believe in Obama's projected growth forecasts, which Krugman supported. Mankiw thought they would be way too high.
Without acknowledging being wrong, Krugman just switched to the Mankiw viewpoint.
I don't know what I think or that I agree with them... it seems to me that what we need to worry about most right now is inflation. I don't think the recent rally was overdone because I think the recent rally brought us from hysterical lows to more moderate lows. I do remain optimistic, as a lot of indicators seem to be at the very least hitting a second derivative point, and a lot of the sources of the credit freeze seem to be improving. Even if credit hasn't unfrozen quite yet, there's a time lag to it all.