Although it's becoming conventional wisdom to think that Rudy's done, I think the overall weakness of the field and the inevitable backlash against Huckabee (already the vitriol is profound) means another challenger will rise. Can a 71-year-old candidate who's never been loved by money-cons (see McCain-Feingold) or Christian conservatives fill the void? Perhaps, but Rudy's humiliation may be more of a flesh wound that a mortal injury. If Huckleberry falters in the face of institutional pressure, as surely he must, someone's got to rise. Rudy still seems the most plausible.
So, what explains Huckleberry? I think this phenomenon is the reaction of an increasingly poor electorate. The media empires and GOP mandarins have spent seven years offering bogus stats to deny it, but most Americans are hurting. Huckabee is the perfect wedge candidate because he appeals to Southern and rurl working-class Christian conservatives--exactly the demographic who continued to prop up the plutocratic Bush regime. If we can take a lesson from Iowa (and that's probably unwise, but how can we help ourselves?), it's that the poor and middle class are jumping off the Good Ship GOP.