I should preface this by saying I'm a complete nonexpert on this topic.
However, this is what the 2008 Nobel Prize for Economics award seems like to me.
1. Conservative academic economists value the nobel prize as a status and achievement symbol. They also value speculating on and predicting who will win it each year.
2. Swedes value feeling higher status than Americans, and two ways they get to experience this is by awarding nobel prizes, and by being regarded as having HDI due to the valuing of economic/social rights not recognized by Americans.
3. There is a cohort of economists where there is general consensus that they are nobel prize worthy in achievements. Some are liberal, some are conservative, some are neither or nonideological.
4. Krugman is a member of this cohort. It is more notable that of this cohort he has been the loudest critic of American conservatives than that he has had the most prodigious achievements within economics.
5. The Swedes in charge of deciding this year's nobel prize winner for economics chose Krugman to send a message to conservatives: in particular conservative economists. The message was something like: we're picking Krugman as a status performance. We're saying we're higher status than you because we disapprove of your politics, we approve of Krugman's criticism of it, and because we get to pick the nobel prize winner of economics and can use it to make points like that.
6. Conservative economists have more or less accepted this status performance because they want the nobel prize in economics to retain and increase its stature and prestige -and they fear a diminishment if they battled over its award this year to Krugman.
That's my layman's suspicion of the nontransparent semiotics and status performances regarding the nobel prize award to Krugman.