Steve Jobs never lets ALL of the cats out of the bag.
Yes Steve Jobs said that they were bought for iPhone/iPod chips. He didn't say Apple bought them for ALL of the iPhone/iPod chips or the entire system board.
The main thing is finding places in those devices that are not fully optimized for performance and power.
The other half is making it so that Microsoft can't continue to buy all the same hardware that Apple is and create another copy cat known at the Zune so easily. Microsoft won't know the specs of these new chips or the programming used for them. Making it hard for other companies with less brains, or at least less ability to use those brains to their fullest, won't be able to copy so easily.
Speaking of copying. You heard about that company, or at least we did at first, that created a Mac clone to run Leopard on ... I would be VERY surprised if Apple didn't also buy PA for custom chips for Macs too so that this can't be done either. The idea would be to ramp up how much it would cost to make a clone until it isn't affordable.
As for what chips will run in any Apple products ... I DO NOT expect them to come out with a cell processor based Mac. BUT I would NOT BE surprised in future years to find out that they have a version of OS X (we don't use "Mac" in the name anymore apparently) that runs on a PS3 or at least cell processors.
This is not to start rumors. Apple had OS X running on Intel chips long before they came out with a computer running on it. Yes this was of course brought over from nExt but Steve Jobs is smarter and knows how to hedge his bets.
Why would he do this other than just doing this? The best reason is parallel computing. There is no better way to learn parallel computing then learning how to program it for the best affordable parallel system out there. What they could learn on that system now could pay HUGE dividends on learning how to program OS X (even for iPhones/iPods) for future Intel with custom PA chips.