I bought the D600 knowing about the problem and hoping I could deal with it. I tried all the dry cleaning methods (Dust Aid, Sensor Pen, and blower) and was able to get most of the spots, but I just could not get all the spots! I'm not quite brave enough to wet clean a brand new camera just yet.
I've had my D700 for over a year and many lens changes and it only had one spot that needed blowing off.
I will give the issue a bit of time to see what happens and will try the D600 again if they fix the issue, but for now I have returned it. I really did love it otherwise!!
Yes, I know sensor cleaning is part of the game, but it really shouldn't have to be something that needs to be done the first week and probably regularly for the first few months.