What's a Trillion Dollars Worth Anyway?

Been lots of posting on the move by the ECB last night.  Looks like the euro went up against the dollar on the initial news and then fell back later in the day (hat tip - Krugman).

I think Felix Salmon captures why here:

Greece and the Euro-zone

Good stuff from Krugman.

Note that his usual critic, Mankiw, seems to think he has some good points.