For .NET, if you are comfortable with XSLT, Umbraco - www.umbraco.org
XSLT qualification is important because it is the basis of the template system (for content), so end users do not have the requirement to use XSLT defining templates.
Edit:
As you move towards the end of 2011, there is now an alternative to XSLT, Umbraco adds support for the Razor engine and its honesty to say that Razor is probably a little less complicated than XSLT (as I continue to be impressed with what you can do with XSLT , he needs a different way of thinking).
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