You may have seen that a new CTP of WinFX has been released -- check out Tim's post for all the links.
However, if you are an WPF enthusiast, be aware that there is no change in the WPF binaries. In fact, the Dec CTP and Jan CTP are binary compatible. I am still digging around to see if there is a difference in the SDK between Dec and Jan, although I suspect the delta is not large. So, if you are only interested in Avalon and aren't doing any work with WCF or WF, you may save yourself the hassle of downloading, uninstalling and installing.