where is the ActiveDirectoryMembershipProvider source

I had heard a rumour that the ActiveDirectoryMembershipProvider source code was available.

I'm having some difficulty troubleshooting the our setup of the out-of-the-box provider, and stepping through the source would have been really handy.

From stackoverflow

• You can get the entire source to the .NET framework using the .NET Framework Mass downloader available at CodeProject. You can find more information on how to use and download it from Microsoft at http://referencesource.microsoft.com/.

• turns you can download the source (delivered as an MSI) from Microsoft. How cool is that!