If you're trying to set up the new shortcircuit feature in SpamAssassin 3.2, but it doesn't seem to work no matter what you do, your local.cf file may be missing this line:
loadplugin Mail::SpamAssassin::Plugin::Shortcircuit
I ended up wasting a fair amount of time troubleshooting this only to find that it was a one-line solution, but one that wasn't particularly well-documented, though I did end up finding it under "perldoc Mail::SpamAssassin::Plugin::Shortcircuit".
The plugin itself is pretty hot. It allows you to define certain spam tests that, if passed or failed, will cause SpamAssassin to bypass all other tests. If a piece of mail is obviously pharmacy spam, for example, there's no reason to run 100 other spam checks on it; just send it on to the spam folder. In previous versions of SpamAssassin, there was no way to bypass tests like this, and you'd end up wasting time and CPU running spam checks that wouldn't need to be run.
So, kudos to the SpamAssassin folks on implementation, but not so much on documentation. Oh well, lesson learned: if you need help with SpamAssassin, check the perldocs first and their wiki or Google after.