I bought a Z2 off of a friend and put it in my 08 GMC Sierra. I realized the head unit had composite a/v inputs. I ran down to the best buy and picked up one of these...

 

 

Now, I get all of my Iphone 4s audio on the head unit... but with the iphone interface... way better. Not only this... but after I performed the 2 wire bypass (luckily my avic was made after june 07) I found that many apps support video out! Like... Netflix, youtube, even some racing games! I ran just enough of the USB to stick it in the 12v for charging.

 

Pretty cool.