More about NAIRU than anyone is likely to pay very close attention to
I don't honestly think NAIRU current "actual" value is what's driving any decision making at the Fed. I think it's more about seasonality, asymmetrical risks and the difficulty of predicting what the next few months of oil prices will be and the implications of that for the economy in general. Oh, and that employment index thingie that isn't "unemployment", but captures people who want more hours and can't get them (U6, IIRC). That's probably driving a lot of thinking over at the Fed. [ETA: and what's going on in Europe, internationally generally . . .]
Anyway. Just in case NAIRU is a factor, Krugman is going to make absolutely certain that everyone knows about how it isn't 5.x% now or at various points in the past. And good for him! Hopefully people are reading and paying attention.