The 3GS offers Voice Control. We're not sure yet why this feature couldn't be added via software to earlier iPhones. Perhaps the voice recognition requires a better microphone than in earlier iPhones or a lot of processing power, or maybe Apple just wanted to differentiate the 3GS.

According to Richard Lai, the "Chinese (Cantonese) voice control works, but took a while to work out the magic words as there is no guide released yet (not out in Hong Kong until early July)." He also tested the "Chinese (Mandarin) and Chinese (Taiwanese), although the latter didn't work as well since [he doesn't] do the accent well."