I get an OutOfMemory error every morning on my test hudson setup. So I'll try to get you the "heap dump" tomorrow. My setup is very simple--a few ant builds from svn with hudson running in tomcat6, Centos(RHEL 5 clone) x86_64, 64bit sun jdk 1.6. No builds run overnight but I leave a browser up with auto refresh on the home (dashboard) page. Reloading that home page all night with no other activity seems to crash hudson.