I have been looking into this too and although I initially was looking at CruiseControl, I heard good things about Hudson and decided to give it a try. I am completely blown away by how easy it was to get started (just download and run) and the configuration is done through the GUI so there's no fiddling around with XML config files.
Within minutes I had performed my first Ant build. I now have it running as a Windows service on a server which is available 24/7 both in the office and via VPN. Upgrading is as simple as downloading the new war file and restarting.
Support for junit reports is out of the box. Installing additional plugins is also very easy and I have added plugins for Trac, Cobertura, FindBugs and PMD. Code and test quality is increasing as it's very satisfying to see the trend graphs rising!
I now use it to manage all of my builds for test and production environments. Since I manage several web applications this gives me more time to spend on actual programming. I honestly can't remember how I managed without it.
