What is a Progressive?

I wouldn't pretend to be able to answer that question definitively, but the inestimable Paul Krugman seems to have provided a clue in Slate magazine recently.

OK, before I get there, a word about terms—specifically, liberal vs. progressive. Everyone seems to have their own definitions; mine involves the distinction between values and action. If you think every American should be guaranteed health insurance, you're a liberal; if you're trying to make universal health care happen, you're a progressive.

Considering we're less than one hour into 2008, I'll let that be my "Happy New Year" message.