I believe it does, you can see the amount gmail uses(in old/simple html mode) towards the end of the page. The same goes for docs, pics & anything else that's connected to your (single)google account. One way of circumventing this would be to use multiple google accounts & use'em for a single purpose like an account for pics, another for docs perhaps one other for gmail & so on. I haven't tried linking multiple google accounts but I think linking them would almost certainly restrict you to a ~15GB limit, give or take a few extra MB for gmail I guess.