There are two hardware changes (from the PowerBooks) that make me think of some hackabilities for the MacBook Pro's. . .
The first factor is the change to the SATA (serial) harddrive interface. Meaning you can have multiple harddrives in serial configuration. In a notebook you could say "so what, there's no room for more than one drive". Except what about the 1" harddrives? Are any of those configed in the SATA format? If so, you might be able to fit four in the space of a standard 2.5" x 9mm HD space(?).
The second factor is the new UltraSlimline size of the optical drive, ostensibly used to make this machine thinner than the PowerBooks. Is the space use maximized? or is there a little more airflow around this thing? (Read "hack-space".)
(BTW when they introduce the HiDefBlueRay CD Burners into the MacBook Pro Line, I think that it will be time for me to upgrade. . . ah computer lust 2007, here I come!)