yeah, it's a coin tray. it has those spring-loaded slots for the coins, and it also has a shallow little rectangular tray, which has the same fuzzy finish as the bit under the ash tray.
it was a tight squeeze getting the cd player in there with the ash tray, so they basically hold each other in there really well.
no idea about a supersize cup! I doubt it though, even if the base fits, the top would probably hit against the dash/cd player. but smaller things should be okay...