The cord they use connects the iPod to a special plug in the armrest, at least on the US model. As far as I can tell, it's the same cord they use for my Scion. It isn't a USB cable, though... something different.
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OEM INFINITI/NISSAN IPOD CABLE - eBay (item 180361436392 end time Jun-01-09 12:29:35 PDT)
Plugging your iPod in with this allows the A/V to run the iPod through the display.
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'Lesca'-2009 370z Touring 6MT w/Sports & Nav-
Platinum Graphite/Persimmon. FLO,IKP,SCG,TMA