PPC turned out to be a mistake. Sitting in 2009 it's easy to make a judgement and say "only an idiot would choose PPC architecture," but Apple made the decision in March 1994 and it looked like a real alternative back then, it wasn't until last last century/early this century that PPC became a real dead end.
But. How do you admit that it was a mistake and hold onto your declining market share? Introduce a new OS designed for intel, but release it on PPC hardware and then when the OS is complete, get rid of the old architecture!
Of course it was made easier by a little mp3 player with a cute name. Mac sales are booming, 1 in 10 personal computers sold in the US is a Mac. There are already more intel based Macs than either PPC or Motorola based ones. Apple survives on pushing the technology beyond it's limits and in doing so it also pushes old equipment into the past.
Sadly this will be true of the iPhone as well, the 3GS that's on the boat from China will no longer be supported in probably, oh, 5 years. At some point the new iPhone/Pod OS X will no longer be compatible with it. But I will have had my use, and, I'm honing my Obj C skills, one good app and my retirement home in the north coast of NSW goes from being a km from the beach to being on the beach!
Yes, they forget all ppc users using osx too but if m$ make it is bad, if apple make it is "different", i dont understand its the same, no?