To clear up what seems to be some confusion here. The reason why Unreal (and hopefully Dragon Age: Origins) have mod support is because Sony allows externally produced game data to be put onto the system by the user. Microsoft has so far not allowed this. So while Microsoft do allow 'mods' in the form of on console made content, they have so far not allowed the installation of PC created content by users.
If Dragon Age: Origin do get mod support on the PS3 it is extremely likely to be in the same form as Unreal, where you get a 'PS3 compiler' for the PC mod tools, which lets you create files that can be transferred to the PS3 with a USB stick or direct download through the browser.
As far as I know a major reason for Sony being more permissive is that their security model is better. The whole PS3 game os is run virtualized as far as I know instead of directly on the hardware, making using mods for hacking the system much harder. Even if you are able to find a security glitch in the mod system you still are locked within your sandbox.







