This is disruptive technology at work http://en.wikipedia.org/wiki/Disruptive_technology Apple's iPad at first looks like a toy that only competes with low-end $600 Dell or HP, but it will acquire a high resolution screen, camera, faster CPU, better software and become easier to use than a real mac and more flexible.

There was time when Mac and PCs were thought of as junk to most scientists because they'd have a high end Sun or SGI workstation costing 5-10x as much that was a lot more powerful. However that market is gone now and realistically the top end computer is now a Mac Pro. What happened was cheap PCs acquired over time all the features of the Sun and SGI workstations.

Apple doesn't want to do this, but the high end Macs aren't going to last forever as a market (and it's already small) and if they don't do it, someone else will (probably Google).