The only things standing in the way of mass migration from OSX to Linux is software and the wireless hardware support. People who've invested in expensive adobe software and bbedit (for god knows why) are vested. They won't go to-say-ubuntu.

However, given that some of us bought the expensive Macs and ran out of money for software, when the broadcom/airport wireless device drivers for linux are stable, you will see a flood of mac users switching.