Professor Krugman, in a valiant attempt to deny that the only effect of QE2 was to raise the price of equities, and more importantly, commodities, advocated the use of "core" inflation measures rather than the headline number.
When headline bled through to core he switched this metric to the Atlanta Fed's "sticky" price CPI (i.e. prices that don't change). I'm not sure how he's going to spin this latest, from ZeroHedge:
There is the CPI... and then there is the MIT's billion price project which, as the name implies, tracks the prices of a billion products in real time. And according to the latter, annual inflation has hit a multi year high of about 4%. Perhaps someone can advise the talented Mr Evans that the 3% inflation he would so love to achieve... has in fact been eclipsed. At least, according to the real world. So take 4% inflation, add $2.5 trillion in "much more" easing, and what you get is only an economic Ph.D.'s guess. Alas, we are unqualified to have an opinion on the matter.
The QE3 crowd is vehement in their denial that they intend to destroy the middle class, that's just a side effect.