iPhone compatibilty with Power PC PB?

I've searched on the threads and other sites, but I can't get the yes or no answer because I don't know what darwin is, etc. Will the iPhone be compatible with Powerbook Power PC's? Or will they make the iPhone availible with two differents OSX softwares?

iPhone is a piece of hardware, not software that has to be compiled for different processors. It will work on virtually all Macs released after the gumdrop iMac G3, and Windows PCs. It's like an iPod.