While php|tek has a definite community or "friends getting together" vibe to it, ZendCon is definitely corporate. It's reflected in the attitude, the clothing (lots of khakis and polos), and the formal exhibit hall, etc. There are still numerous friends getting together, but what happens when you spice things up a bit?
Zend has agreed to a series of unconference sessions at this year's event, around 25 during the length of the conference. Anyone can contribute and anyone can add their topic to the list. It'll be run in a BarCamp style and sessions will be voted on and sessions will be selected by the end of the day. If you'd like more information, check out the unconference page on the ZendCon site.