Unlikely, the processors aren't launched until the middle of march. Anyone looking at waiting should take in to account that it could be early June before they are able to get a 2010 Mac Pro fully setup and ready to work with, and that is assuming the system they buy works correctly.
I think you should check your facts. Intel officially launched Nehalem Xeon on March 31, 2009 but Apple launched the 2009 Mac Pro based on the same chip on March 3, 2009 with early shipments arriving in the hands of customers around March 10th. Based on this track record, if the next generation CPUs are due in March, we will probably see Apple launch the 2010 Mac Pros a few weeks before.