Of course, the argument itself is a pretty defensive one from both sides. On the one side are game fans who passionately want their "new kid" artistic medium to be given the same weighty respect as visual art and literature. On the other side are the anti-gamers who see this new thing as loud, vulgar, and crass, and flatly deny that there's any way good can come of this. The people involved are fighting to keep control of their own little moral islands while taking over the other side's island.
The brilliant bit about the whole thing is that this has all happened before, and will all happen again. Let's make a non-comprehensive and thoroughly un-researched list:
-rock and roll
Both sides are acting as though this fight is utterly unique, when it's really almost identical what happened to all the other mediums on that list. New medium shows up, spends ~30 years developing, many people during that time have this argument, and eventually it settles comfortably into the general cultural psyche until we get to the point that it feels like it's always been there in the form it's in now.
So do I think games art? Of course I do. Are all games art? Absolutely not. Neither are all films, all paintings, all TV shows, or all books. Do I really give a rat's ass if people like Ebert agree with me? Nope. What I do care about is that enough people think games are worth making that eventually we don't have to have this debate at all. What's great is that I think that'll be happening within the next ten years or so.
Now the whole reason that I started writing this post: why I think games are art. If pressed to give a single response to "what makes something art", it would be that something intentionally created is memorable. Plenty of things are memorable, like seeing a guy get hit in the nuts with a football, but that's not art, it's just funny. In order to be art, someone has to consciously create something that has such an impact on another human that it's remembered many years later.
Here's an example from my memory: the game Mafia. This game came out in 2002. It's, unsurprisingly, a game about a guy who accidentally finds himself wrapped up in the mob. In the game, you first see him as a cab driver who gets drafted as the getaway driver for two made men. After impressing them with your driving skill, you get "invited" into the family. The rest of the game charts your rise through the ranks as you kill and steal your way through a '30s era not-Chicago. Along the way, you fall for a girl, and eventually decide to get out by turning snitch on the mob. Miraculously, this works, and you escape with your family into the arms of suburban American to start your new life.
Here's where most games, and movies for that matter, would end. Mafia doesn't, and that's the vital bit. In the epilogue, you see your character as an old man. He seems happy, having made it out of the mob to live a good and happy life. He goes to the diner, and sits down for a meal. A man walks up to you, says "Salieri sends his regards", and shoots you in the head. But rather than being a cheap "oh, your character dies, ha HA" ending, it's actually bittersweet. Yes, you died. But from the moment you joined the mob, that was likely. You got a full life. You raised a family outside of the chaos they would have been in. Yes, the mob caught up to you, but did they win, or did you? It's bittersweet and complex in the way that great art is. And most importantly, I remember it eight years later. That's what art does.