PS3 can run Linux. So yes it is possible, the only reason it is not done, because of pirating/hacking users, not Sony or Microsoft. Look at what happened to PC market with too much freedom.
If you dl'd the update from around 1.5 years ago?
You can't run linux on it without reformating the HDD back to factory standards.
If you have a new one? S.O.L
As to the topic at hand?
The only way its going to console, is if gamesas, takes the highest rated 'mod' uploaded through steamworks, and personally re-works it to work it ont he console, to make sure it doesn't cause it to explode.
And while the PC version doesn't have to much access to the OS?
The 360/Ps3 one? Yea... It be very easy to make it explode if you knew what you were doing. (I use the term, Explode mostly for the imagery.
That said, there is only ONE case where PC mods were 'free' and Useable on the PS3, and that was UT3.
The problem?
NO one ever freaking used it!
Basically you used the PC editor, made a map. You had a certain amount of resources you could actually use, save the map, and 'port it to the Ps3 file version.
You could then put it on a USB, and toss it on the ps3.
Supposedly there mod editor 'checked' how much resources those maps actually used, debugged it, and prevented it from converting if there was some kind of conflict.
Gameplay tweaks? impossible.
New Assets? Impossible.
Bunch of stuff? Impossible.
And of course... no one used it!