I read somewhere the PS3(older ones anyway) had been in a sense hacked to play backed up PS3 games.
Can't find it though, might have been removed due to invalidity.
Basically it said they added Linux and then used Linux to copy the game data from the PS3 disc to the HDD, then played the game from the HDD in the PS3's XMB. The article claimed it took 6 hours to copy all the data to the HDD though.
I for one would not waste my time fooling with that and imagine the HDD space required for a bunch of games. Some games might be 25Gb or more if DL disc.
Another article though on the official playstation forums claims that any Linux distribution will not copy the data to the HDD.
Only thing I found about it PS3 Hacking Has Begun - Hacking - Kotaku but does not give full details like the one article.