Sony already announced that they sold 1.4M in North America in November (well not exactly, but they announced it on December 3rd, so most likely November's sales). Of that 1.4M, at least 1.1-1.2M will be the US alone.
Microsoft announced that they sold over 1M worldwide within 24hrs of their launch. I think at most MS allocated 700K to the US for launch. The US probably received another decently sized shipment before the end of November (or they reserved a bunch for black friday) but I can't see them shipping another 400-500K+ within 8 days.
I think Sony will win November's NPD, but MS might win December's NPD. Right now it does seem like MS has more stock in early December, so unless Sony can get another sizable shipment to the US, I see MS taking December's NPD. Worldwide, I think Sony will retain a comfortable lead. As it stands right now, I think it's ~2.1M vs ~1.5M. Not that it matters much at this point.