After my post two weeks ago I was contacted by Dmitri Maximovich, author of the CruiseControl extension for FireFox, who was interested in extending its support to the .NET version and wanted to discuss what exactly doesn't work. It didn't take him long to figure out how to fix it and yesterday he released an updated version. You can find it here. Please report any problems you find. Any suggestions are welcome as well.
On the technical note, the extension does it work by parsing the HTML of the web dashboard, so it can be quite fragile in case the page structure changes. I do know that both CruiseControl teams plan to add REST XML web services but this will take some time.