Hudson
The Sonar team has an instance of Hudson running. Hudson is a fantastic open source continuous integration server.
Here are some links:
Architecture Rules on Hudson
http://ci.sonar.codehaus.org/job/Architecture rules/
Build Status RSS
http://ci.sonar.codehaus.org/job/Architecture rules/rssAll
Modules
http://ci.sonar.codehaus.org/job/Architecture rules/modules
