You can still download it.
Microsoft.com says you can, you can see it under ASP.NET Samples
http://www.microsoft.com/resources/sharedsource/Licensing/Developer.mspx
And this is the place to download it:
http://www.asp.net/Forums/Download/
It wasn't very easy to find, I don't think they want people downloading it anymore. I says it requires the .NET Framework 1.0 so it doesn't look like its for 2.0
. Telligent probably took over the project before then because Community Server 1.x was built
on ASP.NET 1.1.
EDIT: Just made the URLs hyperlinks; I always forget to do that because the toolbar doesn't work in Firefox.