It is a scripting language, albeit a powerful one. Depending on what we can and cannot change within UT3, this could be the door "homemade 3D games".
Mind you they will still be considered "UT3 Mods" but we have no idea what liberties are given to us. It may very well be possible to program a simple menu, that loads up a different "level" with scripted sequences that makes up a "different" game.
Looking at it from outside the code, it will seem as though we are loading up different games; in actuality it would be simply loading up different levels for UT3.
The point is, this could end up being a very cost effective, KOSHER form of "Homebrew" on the PS3.
As well, the immediate benefit of this is that we have a great 3d engine to run these games off of. Imagine, for instance, Super Mario War 3d, using UT3 on-par-graphically models of Mario, Luigi, etc, jumping about in a sort of Platformer scenario.
Mods like this exist for HL2, so they should be possible on UT3.
Again they would be mods, technically speaking, but it would give the illusion of being "homebrew" and Sony nor Epic would mind, since we aren't breaking any laws or rules or using the system in any illegal fashion.