Telligent have released Community Server 2007 and with it the SDK - basically all the source code for the product. If you want to do any development for this new version of CS, you'll need to download this and get it working. It's all manual install though and as Dave Stokes hasn't managed to update his install guide yet, here are some rough and ready instructions for running it from scratch using SQL authentication with the database.
NB. This is a VS2005 SP1 \ ASP.NET 2.0 project only now, so no more VS2003 support.
Download the SDK from...