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It wouldn't surprise me if an accessory like that will ask if you want to go into airplane mode, but it should work, assuming they use USB charging and not Firewire.

Also remember you will have no way to control the tracks with this. I bought the LiquidAUX for iPod and iPhone, I don't know if it works with 3G yet, but it does "work with iPhone". Also it comes with a remote that attaches to the steering wheel.
 
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