I tried it earlier this week. There was a dock piece in there that fit the iphone pretty well, and it did charge despite the error warning... but it's not made for the iPhone and there isn't a perfect fitting dock piece in there for it... I returned it although mainly case the arm wasn't long enough for me.
Thanks that really helps. I also just got a similar reply from griffin.
Product: tuneflexaux06
Question: Hey, can you confirm if the tuneflex aux 2.0 will play audio and charge an iPhone 3G, im aware its not officially supported as of yet, but does it work for my use at all?
Answer: It will charge your phone and pass the audio through, but because there isn't an adapter to hold it, I can't really recommend it. Because Apple has to approve anything we make for the iPhone first, there will probably have to be a separate model made just for the phone. We're not allowed to sell adapters for non-approved products. If you're able to securely hold the phone in place, however, this is not an electrical reason it would not work. You will encounter the "AirPort mode" screen.
Thanks for your interest,
Rachel
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Griffin Technology, Inc.
Technical Support