Today I replaced our CruiseControl install with Hudson. CruiseControl has served its purpose after doing its duty for 2.5 years with us. The reason for replacement was it got very flaky with builds and sometimes would just hang. Hudson has done 11 builds today with no glitches whatsoever.
Hudson was trivial to deploy and configure and it’s got a shiny UI. 
If you’re in search of a continuous integration system, FOSS is important to you (and it should be), checkout Hudson.
Our Parabuild may be worth a look if you are looking for a quality Continuous Integration system. Parabuild is free for Open Source projects.
Sergey