Simone Chiaretta, a member of the Subtext team (not to mention many other projects), just released a Vista Gadget which allows you to monitor a CruiseControl.NET build within your sidebar.
It looks spiffier than the system tray applet that comes with CCNET.
Here’s a screenshot of it docked.
From the screenshots you can see the status of the projects he is monitoring. The good news is that the 1.9 build has been fixed since he took these screenshots.