The difficulty with the term "art" is that there is no tangible method or criteria that can be used to say, "Yes, this is unquestionably art." Picasso might be considered the consummate professional artist, but many will tell you that the chap taking a piss on the storehouse wall has just as much claim to the moniker of artist as Picasso or any other renowned artist. Having said all of that, let me offer up this definition of art:
"Any created piece or work that wholly represents the creator's vision and has not been tainted or altered by any external force."

This definition covers the Picassos, as well as the struggling artists of the world. If we examine videogames in that light, we have to sadly say that in the majority of cases they would not be a work of art. Understand that this comes from the perspective of someone who is heavily into videogames and most certainly would love to see the day when a group of videogame programmers release a creation that has not been touched by outside elements. As an example, I offer up ICO for the PS2, a game that many consider avant-garde. It comes as close to the definition of art as any videogame I have ever seen.
But, does it hold up to the definition we have above? What if the developer had originally envisioned a young boy protecting and guiding...another young boy, rather than the beautiful girl portrayed in the game? Perhaps the marketing department would have said, "We will sell more copies if the game is about escorting a young girl instead." One inexorable fact about the videogame industry is that plenty of hands are in the cookie jar, but most of those hands don't participate in the baking process. Elements of a game will often be added or removed to make it more attractive to the consumer. And because of that one, simple fact videogames would not qualify as art.
Latest PC game demos
Supreme Ruler 2020 An impressive demo-nstration of the forthcoming geo-political war simulator. (355 MB)