I retired from personal blogging in July 2008 but you can find me over at blog.xero.com
Follow @roddrury
Does anyone have any recommendations for open source .Net & SQL Server Community Forum software that we can integrate into our application?
A key requirement is the ability to have single sign on from our application to the forums. Simple is good.
If someone is working on something similar, or wishes to build a product we’d be interested in working with you.

http://communityserver.org
Rod, we have some .NET forum software we have developed; email me
Have a look at what Marshal Software uses for their forums and knowledge base. If you need someone with Marshal to talk to flick me an e-mail.
http://pmwiki.org
Rod, have a look at DotNetNuke. Uses .Net and SQL and is fully open source. Great for development environments and has loads of modules for community portals. You can go a long way without re-inventing the wheel with this platform and integration with Xero should be quite easy.
Hey Rod,
We recently used Community Server for http://www.texture.co.nz. It was a great package to work with. We added some extra functionality and a pretty decent skin. We are also using this in another project using a single sign-on. If you’d like to know any more then let me know and I can put you in touch with Rob, our senior developer.