On the Zend Developer Zone today there's an announcement from Ralph Schindler about this month's Bug Hunt Days (for June 2010):

It's that time of the month again- but this time with a twist! Today [June 17th], Tomorrow and Saturday, 17-19 June 2010, Zend Framework will host its monthly bug hunt. You read that right! We are adding Saturday into the event for those developers who want to do a little weekend bug hunting. For those of you unfamiliar with the event, each month, we organize the community to help reduce the number of open issues reported against the framework.

They've added the Saturday onto the end of the days to give more people time when they're away from work obligations and can spend time closing the bugs they want. If you're interested in helping out these next two days, you'll need to have a CLA on file, have read over the guide to get started and possibly drop by the Freenode IRC channel (#zftalk.dev) to talk with other bug hunters and Zenders.