There has been an ongoing feud between Barack Obama, the candidate for the Democratic nomination for president, and Paul Krugman, the NY Times columnist and eminent economist who was almost the only progressive voice in the mainstream media immediately after 9/11. It basically boils down to Krugman saying that Obama is not progressive enough on the important issues, and Obama not responding in any meaningful way at all, but rather his campaign ignoring the issues and attacking Krugman personally (or otherwise just evading the issue) instead.
It's all best explained here:
Obama stump speech strategy of conciliation considered harmful at http://www.correntewire.com/obama_stump_speech_strategy_of_conciliation_considered_harmful
Here's a great teaser quote:
Obama: The system sucks, but I’m so awesome that it’ll melt away before me.
Edwards: The system sucks, and we’re gonna have to fight like hell to destroy it.
Clinton: The system sucks, and I know how to work within it more than anyone.
So, please go over there to read the full article, and let me know what you think in the comments.