Here's some good news from Sony - they say that there will be no DRM on the PS2 or PS3 disks that would prevent you from playing a game on arbitrary Sony consoles:

However, in order to give an official answer to an already increasing wave of unrest among the gamers, Sony Computer Entertainment Europe has stated, through one of its' spokespersons, that "this is false speculation and that PlayStation 3 software will not be copy protected to a single machine but will be playable on any PlayStation 3 console".

Seems that someone learned a thing or two from the savage beating they've taken over the last few weeks.