same here...
I'm having the same trouble. Which is a complete PITA as I would never charge my phone during work, but in the long commute I would plug it in and be able to listen to my tunes and charge my phone. The problem that I see with this, is that if I'm going down the road and charging my phone (on a very old USB/12 Volt converter with a 4th Gen iPod cable), I'm not able to hear an incoming call or message. Previously with the KCE-422i cable, the music would mute slightly and allow me to be notified when something was coming through.
So, I'm following what you are saying about the firewire support, but given the fact that I can still use my old 4th gen USB cable to charge the phone just fine, this tells me that the pinouts are the same as they used to be. It appears that Apple didn't consider all the legacy cables and accessories out there with this version of phone. My girlfriends iLo car charger device purchased just a few months ago for her car and iPhone now doesn't work at all (same message about not supporting charging).
Hopefully Apple will release an update soon like they did last year that allowed the Alpine head unit to charge and play. But if anyone else has any ideas, I'm all ears.