Integrating chips everywhere...
I don't really think it's going to be limited to the iPhone/iPod Touch, there's just too much money being invested in expanding hardware development expertise even for as big as the iPone/iPod market is. Apple isn't bull-ish on the netbook or tablet market either. PASemi was so valuable to to Apple, for some reason, because of their "Instant-On" and full computational arsenal available only when needed/as needed tech. The PASemi tech was thriving in server RAIDs and Apple pulled the plug on those developments conceivably to eliminate future competition, also there are significant numbers of complex custom built military computer systems built around these processors. Add in Apple's obsession with heterogeneous cpu/OS solutions and the picture looks a little different to me. Apple's been offloading more and more of it's Quartz graphics to the GPU for a couple of years, but neither ATI nor Nvidia have proven to be reliable partners with respect to build good basic drivers for their hardware and they expect more of the same from Intel. I don't think they want to have so much of their functionality dependent on third party hardware anymore.
Ultimately even though Apple's been able to drive down their costs and expand their product lines with Intel processors they probably still haven't reached the theoretical peak of their "ideal" hardware set. Personally I think Apple is interested in moving most of their hardware back to being closer, architecturally, to embedded systems which can increase stability and performance by great magnitudes...it's just a matter of keeping the OS general enough and finding that balance.
I think Apple's goal is to have a custom processor in every computer product they develop. Here's a heterogeneous computing article that gives some ideas about the benefits of designing hardware differently possibly using x86 cpus as a base system component.
Heterogeneous Computing (not a lot of info, but definitely somewhere to start the paper trail)