This news has come to us in the form of a build tag which sports the typical naming scheme for milestone branch builds. 7048.winmain_win7rc1.090211-1625 is the tag. As you can see, this build was compiled on February 11th 2009 at 4:25 PM. On one hand it is good to see Microsoft moving this quickly with the development of Windows 7, but on the other it is a little concerning.
Microsoft has only officially released one build (7000) which went to beta testers and the public alike. One build is not enough to gather enough feedback to move ahead this quickly IMO. Windows is a far more complex piece of software than Office and I hope Mr. Sinofsky can learn that before this beta cycle is over.
News source: GeekSmack