I just came across this nice little gadget that Microsoft offers to be used on your Vista desktop. It counts down the number of days until the "2008 Global Launch Wave" which will start on wednesday February 27th 2008. Windows Server 2008, Visual Studio 2008 and SQL Server 2008 will then all be launched. Considering the fact that they came up with this gadget themselves, they must be pretty sure about this date. :)
You can download this gadget here. Note that the actual gadget will indeed refresh the counter, as the image in this blogpost will not.