Microsoft plans to speed up the life-cycles of their operating systems: they now aim to come out with a new OS every three years.  In a talk in Miami yesterday, Mr. Microsoft himself, Bill Gates, said that the new  version of Windows will come "sometime in the next year or so" and that he was "super-enthused about what it will do in lots of ways."

This likely does not mean a retail release is coming next year though; instead, Gates probably meant that the development of the new OS will have come to the point next year where they have a functional, working internal version of Windows 7 to  evaluate.

But it does seem likely that the next Windows could come as early as the first half of 2010.