I would expect a new case design in the next few years. Apple has typically been slower to change the look of their “pro” products as opposed to their non-pro. The iMac and iBook/Macbook both have changed more often then the G5/Mac Pro and the Powerbook/Macbook Pro. But they have updated their pro products even if they look the same. The new ones have LED backlighting and a multi-touch touchpad, both of which are under-the-hood upgrades, but upgrades nonetheless. They are also continually upgrading the specs in terms of HD space, CPU speed, etc. I don’t think the iPhone has anything to do with the timelines of the computer hardware though- they are separate departments, more so then the software side of things.