Windows Presentation Foundation, my friend Avalon, has (conspicuously) yet to receive its Go-Live status. In fact, there were no changes to the Avalon binaries between the December and January CTPs.
Here's why we have to wait a little longer to see Avalon go-live in glorious technicolor. [Update: And Michael Swanson summarizes some thoughtful articles about why, when it's released, WPF will dominate thick client development.]
From the WCF and WF perspectives, this is amazing news. Download instructions for the CTP are on this page, and please be sure you're clear on what it means to be using a Go-Live license by reading this.