See http://www.microsoft.com/downloads/details.aspx?FamilyID=4ad85860-d1f4-42a1-a46c-e039e3d0db5d&DisplayLang=en for the download, or if you just want to see what’s changed you can review the documentation that can be downloaded from http://www.microsoft.com/downloads/details.aspx?FamilyID=f1bae135-4190-4d7c-b193-19123141edaa&DisplayLang=en. (It’s still replicating to all the download servers so if that link displays a “not found” page try to refresh the page again.)
Note that MDT 2008 and ConfigMgr won’t work with this new version of the Windows AIK. A beta release of MDT 2010 will be available “real soon now” to remedy that, for those of you who want to start playing with the betas.
For those of your who are “hard core” you’ll notice a new utility called DISM in this new version of the Windows AIK. You’ll come to know this utility fairly well, as it replaces PKGMGR, PEIMG, INTLCFG, etc. It adds new features too. Definitely check it out.