From Somasegar’s blog:
The .NET Framework has always been at the core of WinFX, but the WinFX brand didn’t convey this. The WinFX brand helped us introduce the incredible innovations in terms of Windows Presentation Foundation (WPF), Windows Communication Foundation (WCF), Windows Workflow Foundation (WF) and the newly christened Windows CardSpace (WCS) formerly known under the codename “InfoCard.” The brand also created an unnatural discontinuity between previous versions of our framework and the current version.
With this in mind we have decided to rename WinFX to the .NET Framework 3.0. .NET Framework 3.0 aptly identifies the technology for exactly what it is – the next version of our developer framework.