Umbraco looks pretty amazing!  It may not have the following of Dot Net Nuke, but it looks to be a lot more open to web standards.  I've tried many times to really like DNN, but it just pains me that I don't have really clean CSS control over things.  I suppose it's because I haven't gotten my head around it fully, so I'm sure I'm missing something.  But don't tell me to use their non-standard (although open source) theming system.  That just doesn't sit right.

Anyway, back to Umbraco.  it appears to have support for web standards, full API, and a very extensible platform!  I haven't looked at it in too much detail, but at least its something new!  Something outside the standard DNN, Rainbow, Joomla, and Drupal CMS systems.

Once again, I'm no expert at any of these, but I'm always on the lookout!