I know it's early days but just a heads up, the beta 1 of iOS 5 doesn't work with the latest AMI firmware. All media controls are disabled, only control is via the device itself (as though you were playing sound from a video or another application).
Unfortunately it's actually Audi that need to update their firmware for compatibility, not Apple. My company designs and develops entertainment software on a number of platforms including iOS, so I will try and dig through Apple's developer support and see if we can find out what has changed this time around.
Just a heads up for those considering trialing the beta for non-development purposes, or for those excited about the update's release coming this September.