Today http://orchard.codeplex.com/ went live. Orchard is an open source Content Management System that the folks from Redmond are working on together with the ASP.NET community, and which I've been following with much interest. Orchard is based on ASP.NET MVC, which means I'd favor it over something like Umbraco when it is mature enough. Why? Because this should mean that it blends easier with your regular development efforts, rather than having to deal with an entirely different templating technology. Umbraco for instance uses XSLT, and even though I wrote a book a about XSLT and my company is well versed in XSLT because we do a lot of BizTalk, it is troublesome for plain ASP.NET developers.

Keep in mind that Orchard is relatively new and a lot of scenario's are still not supported. But at the pace the team is going, you'll soon see more advanced stuff being possible. You can make yourself heard about what you'd like to see through CodePlex or through one of the sessions at TechEd or PDC this month.