Yep, here's the response direct from Onkyo:
"The Onkyo ND-S1 was certified at launch for:-
iPod touch (1G and 2G), iPod classic, iPod (5G*), iPod nano (1G*, 2G, 3G, and 4G)
So the ND-S1 is not officially certified for the iPhone 3GS/4 (and Onkyo has never claimed otherwise) though in practice it will play back content from them and charge them... but you will invariably need to have the device in Airplane mode to avoid pops and clicks (metal objects within the vicinity of the iPhone's antenna can act as a ground plane).
BTW, there appears to have been a separate issue affecting Apple devices and all digital docks in general but iOS 4.2.1 appears to have remedied that.
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