I haven't heard of anyone being offered anything
You'll find this is down to generally two things.
1) They want to know theres a real person there with credentials and not just an Alias
2) They will tend to prefer someone who is willing to strive and come to them and be enthusiastic in wanting a job with them.

I'm speaking here purely from the artist's point of view since this is the main "modder" criteria. Joylen Webb, Creative Manager of Blitz Games (formerly worked for Codemasters) did a small fill in presentation at SAND 2006. His presentation was one that they give to students they take on invitations to the company. He listed that the following things were needed to be a game's artist
- Traditional Art Skills (understanding on tones etc., helps if you can draw etc.)
- Ability to produce 3D models
- Ability to produce Texture Maps
- Have some ability to rig a model if called upon

and on a slightly more sutle side

- Have an element of "human-ness" (essentially they seek candinates that realy want to be there)

They also like to see how you can break down what you've made for a game (Original Wireframe, Original Mesh, Normal Mapped/Bump Mapped Mesh, Textured Mesh, Texture Maps, UVW Unwrap)

I'll personally be starting to apply to all the british games companies come summer 2008 when i get my degree [BAHons] as a games artist. Using this technique.

------

don't tell me 'modders will not be able to edit or replace these files...because the format is optimised specifically for rendering'
thats generally what their tools do, the format compresses into a file type for faster rendering (or something along those lines). Perhaps getting the compiled meshes back out of the compressed format is indeed complex but the original files that go in are still made in max, maya, xsi, photoshop... It would take someone from CA to clarify this. I dont pretend to know much about game engines as such, just how they utilize assets.