If you haven't gotten a chance to participate in one of the Zend Framework Bug Hunt Days, you can get up and running pretty easily with this guide from Padraic Brady that introduces you to the concept and includes a few helpful hints to keep in mind when you participate.
Every month, the Zend Framework now holds a Bug Hunt, a period of about two days (usually a Thursay and Friday after the middle of the month) when everyone in the community is invited to assist in resolving (or reporting) issues to the Zend Framework Issue Tracker. The next event will occur this week on Thursday 19th and Friday 20th November - so there's no time like the present to get yourself familiar with the process.
He looks at why the developers chose to go with a bug hunt (to help make the framework better for everyone, the work needs to be done on a larger scale) and why your should take part in an event. He shares some tips on getting started - visiting the IRC channel, using the issue tracker, ask questions and a few others. Be sure to check out the last part of the post for his helpful tips on where to go from here.