Yes, its for a plastic trash bag. I think its one of the best ideas ever. If you travel with little kids and the better half, that hook on the dash will keep your interior from being covered in granola bar wrappers, chewed gum, gummie bears, empty water bottles, etc. Then when you stop for fuel, you simply drop the whole thing in the trash.
I think one of the minivan designers must of helped with that feature, but that person is a genius. Its also at the proper height, so the throw away bad hangs real nicely...
I get excited about really odd things... :-laf
If you check out the new Freightliner Cascadia, it has a similar hook, only its even nicer. It folds out of the way when not in use.