We are currently using SVN, and we are storing much of the artwork (sounds, images) in our repository right along with everything else. Right now, the artists commit their work to the repository directly. When the artwork is approved, it is linked to the codebase.
We want to keep the checkout process simple (so that artwork doesn't have to be installed/configured separately) but we would like to streamline a process where the artists who produce the images can submit their work somewhere independent of the main repository, and after it gets approved it is put into the main repository. We want to make it as simple for the artists as possible without much training.
How does your company typically go about streamlining this? What software do you use?
What teams I have worked with have done in the past is to break up the repository in Subversion. So, for example:
/repository/trunk
/project_name (this would be your project)
/artwork (artists work out of here)
Then, the art team only checks out the artwork branch and works from that and the developers work from the project branch. It's the responsibility of one of the artists (the lead, typically) to check-in finished artwork to an 'art' folder (or images, or media, etc) underneath the project for use by the developers.
While it's not automated, we have found that it works pretty well because it separates the concerns, but still allows the teams to (ultimately) work together.