Recently our Developer Division chief Somasegar blogged about the rebranding of WinFX as .NET Framework 3.0. The blog can be accessed from: http://blogs.msdn.com/somasegar/.
As it stands now, .NET Framework 3.0 will have a dependency on .NET Framework 2.0 with CLR, ASP.NET, WindowsForms, etc versioned at 2.0.50727.x. It is not yet clear if the current WinFX(beta2) library versioning scheme will continue or it will be changed to 3.0.xxxxx.x. The new member of the WinFX family is Windows CardSpace (WCS) that gets packaged into .NET Framework 3.0 along side WPF (Windows Presentaiton Foundation), WCF (Windows Communications Foundation), and WF (Windows Workflow Foundation).
Early information suggests that .NET Framework 3.0 has a runtime dependency on .NET Framework 2.0. Customers who already evalueated and standardized on .NET Framework 2.0 need not go through that elobarate process again for .NET Framework 3.0 as it is only an additive release, but a significant enhancement to the framework. Framework 3.0 eval has to happen in the context of the applications wanting to take advantage of these technologies.
.NET Framework 3.0 (formerly WinFX) will be available for Windows XP as well as Windows Server 2003 in addition to Windows Vista.