In response to a comment in the last post, I'll add that there ARE in-house musicians at most big studios.
Audio Guys-This is a job for people good at mixing sounds. You may not need to play any instruments as long as you can put things together in the computer, but instrument talent always bolsters what you are able to produce. You don't just do music, though, you'll also be in charge of converting audio from audio libraries into different formats for use in different game engines and cutting audio into the usable/needed parts. And don't forget recording...Many games require voice and possibly other sound effects recorded with a mic. You might just work out of a small room with a little sound insulation, but that's all going to depend on where you go.
Artists- Let's break this up into parts, because there are lots of kinds...
The title "Artist" might apply to you if you, like me, work at a small operation and you pretty much do everything. Otherwise, at a bigger studio, you will get a different title.
Concept Artist-Concept artists usually are very good at using digital painting programs to make the kind of flashy stuff you all like to put on your desktop background. They need to take a few written notes from a design document about characters and environments and imagine the ultimate incredible scene as it might look in the end. They also need to expect the final product to look absolutely nothing like the awesomeness they envisioned.
UI Artist-Creates and designs the life bars, frames, menus, and buttons that go into a game's User Interface. Should be pro at Illustrator, Photoshop, and a little motion graphics like Flash or After Effects for some of the more polished, cooler stuff. Expect to redo the interface 2 or 3 times, since no matter how cool it is, by the end of the project, someone will get bored of it and decide that's because it wasn't as good as he originally thought.
Character Modeler-Must know Maya and/or 3D Studio Max typically, and have a knowledge of how to create characters that animate/blend well. You'll also want to know how to get your character to look amazing, even with a polygon count limit. For low-polygon models, that means less than 500 triangles usually. For hi-res stuff, you may get up to 2000, 5000, maybe even 7000. But you'll want to also understand mapping UV's for texturing, painting texture maps, painting specular maps, and painting normal maps. You'll be working with model exporters that are sometimes built in-house, because game engines don't use maya binary or max files directly.
Environment Modeler-Much like a character modeler, but you are expected to make environments that fit the poly-count limitations and keep everything within a certain art style for the environments. You may also have to do lots of environments very quickly.
Technical Artist-Can mean a number of things, but I think most common is for this person to be in charge of adding rigging (animation functionality) to character models. They also write scripts for 3d software that aids in production for the other artists (or themselves) to use to speed up those dull, repetitive tasks.
Animator-This is what I used to be...Usually means taking 3d modeled, rigged characters, and making them do all the actions they need to do in the game. Can also include cutscenes, but sometimes there is a whole other position for that "Cinematics Animator". I got to do a little pixel animation as well. The "funnest" part is trying to use animation exporters which turn your animation data into usable game data.
Storyboard Artist-This person visually plans out the game's cutscenes, he usually has to work from a script and he should have a great knowledge of cinematography (camera angles, types of camera movement) and he should be able to whip out cool drawings in all kind of perspective very quickly, showing lots of character emotion.
2D Animator-You don't see this much any more. I was just an animator and I did this a little bit with pixel animaton. 3D animation is much cheaper to make now, so learn the 3d stuff if you want to make games professionally. 2D is still cool though, so having this as an extra skillset will help.