Notice: Pending mods now under review!
For the record, about the only things that *should* get rejected are obscene or blatant copyright/IP infringement (i.e., photgraphs of actors, soundtracks, video clips, etc.). If it is anything you created yourself or got from public domain/open source sources, it should be fine.
Also, please do not include unchanged graphics, etc, that are arleady in GC2 in your mods (such is just extra downloading for nothing, and potentially makes GC2 content available to those who have not bought the game). In most cases you can simply reference the existing files and it'll work the same.