AtomSite can be used as both a CMS and blog engine.
AtomSite is built using the ASP.NET MVC 1.0 framework, just released this week. It has some really nice features such as composite widgets, a theme view engine, plug-ins, OpenID, and more.
The source code is available at:
http://blogsvc.codeplex.com/Release/ProjectReleases.aspx?ReleaseId=24915 or http://atomsite.googlecode.com/svn/trunk/
Also, I'm looking for some help on the project if anyone is interested in joining the dev team.
Thanks for any feedback you may have.