spamassassin-3.3.0-beta1 is out. This is very close to what 3.3.0 final will be. 3.3.0 trunk has generally of better quality in both stability and spam detection capability than 3.2.5 for many months now. I personally have been running snapshots leading to this beta release on my production RHEL5 server since early 2009.
RHEL5: I personally am using these scratch builds. USE AT YOUR OWN RISK, but feel free to file bugs in RH Bugzilla and assign it to me. You will need some new perl module dependencies from EPEL5. The plan is to push spamassassin-3.3.0 final + new perl modules to RHEL-5 sometime during 2010 after extensive testing. I especially need test feedback of systems currently using spamassassin-3.2.5 with Mailscanner, Amavis or Mimedefang.
Optional packages: These packages are not required, but they probably will improve your spam filtering results.