Just got invited to the blog and midnight is rolling up on me faster than I'd like, so I will make this short.
As so many people have stated before me, art is art; what separates "Fine Art" from "Graphic Design Art" are simply what we as human beings perceive. We may not know the name of the creator behind our favorite billboard, but you can be sure an "artist" was behind its creation. Sure, Graphic Designers are creating art for a client or company, and may be given guidelines on what the buyer expects, but in the end it is what that person puts on paper that turns into the finish product or "piece", that they think will move people. So maybe "Fine" artists dabble in whatever they please and present whatever they want on canvas and label it "fine" art, but that doesn't mean it is any more enjoyable, peaceful, tranquil, moving, exciting, etc, than a piece done on a billboard.
All in all, it comes down to each individual's perception of what "art" is, and we will all have different views; its inevitable.
Just to throw my two cents in; there are some soda advertisements that I would hang on my wall before a few of the "fine" art pieces I've seen. :)