Having sent out a rapid-fire announcement of the Jan CTP, I wanted to provide a couple of snippets of additional detail covering this release.
Firstly, this release of the WinFX Runtime Components marks another major milestone for us as we progress towards a launch. In particular, we're offering Go Live licenses for Windows Communication Foundation ("Indigo") and Windows Workflow Foundation. You may be wondering why we've not also offered a Go Live license for Windows Presentation Foundation. We are planning to offer one in a couple of months' time, but naturally we want customers to have a secure, reliable, polished experience with WPF, where they can have confidence that installing WinFX won’t break their environment. Since WPF is entirely client-orientated, any production app could be distributed to many machines of differing configurations and environments, and we want to make sure that we can service these moving forward without requiring a reinstall of the OS or breaking any other apps on the system. Our goal is to have something available in the next couple of months.
Secondly, it's worth pointing out that this release doesn't actually contain any changes to the WPF component. We've been working on a separate branch and for various reasons that have to do with integration with Windows Vista, we're not easily able to expose those changes in this release. There's a lot of platform work that we'll make available soon - hold tight! On the other hand, there have been improvements to the SDK and of course the "Cider" integrated tools in Visual Studio are a great improvement on the basic facilities that were available in previous releases. The good news is of course that any code you've written or downloaded for the December CTP will run quite happily on the January CTP!
Lastly, and this is a one-off only, it is possible to install the January 2006 CTP of WinFX Runtime Components on Windows Vista. Normally this isn't possible because the Windows Vista bits are tied to a specific release of WPF, but since the WPF bits haven't changed, it is actually possible to uninstall the in-box WinFX Runtime Components and install the new components from the link provided in the previous entry.