Chris Anderson, Chris Sells and Tim Sneath are all talking about the latest version of Avalon being available for MSDN subscribers, so I logged into the downloads and looked a bit but no luck. Then I decided to do a text search on the source of the Downloads tree and I found it! For those of you who are having problems finding it yourself here is where you find it:

Tools, SDKs, and DDKs > Platform Tools, SDKs, DDKs > WinFX SDK - Community Technology Preview > WinFX SDK - Avalon - Community Technology Preview (English)