The Denver Post (Via OPP) is outing Skype's plans to port their mobile VOIP application to the iPhone. They cite the need to lower power as the number one barrier to entry. Whether this is Apple's barrier or theirs wasn't clear. Also not clear was whether or not the Skype would work over AT&T's 3G network or only over Wifi. Optimism is low because Steve Jobs said at the launch of the App store that Apple (he) was not opposed to VOIP applications so long as they run over Wifi.
Although it wasn't mentioned in the article, the application would likely work on Apple's 2G