I asked a similar question about Krugman in this thread:

http://news.ycombinator.com/item?id=656995

The issue was a little bit different. I quoted him saying East Asia had no chance of recovery without currency controls, and being exposed as wrong within two years. I asked why he's recognized as a mainstream economist when he's so consistently wrong.

I got some great responses. The general consensus is that Krugman had made some valuable contributions to the study of international trade, but that he's pretty openly partisan and his popular economics and theories aren't so hot. That's a big paraphrase, there's lots of details, comments, and links in that thread if people are curious.