Here's a fairly good article about the potential of games as a medium for storytelling. I'm actually in the process of writing an essay on the same topic, and it is always refreshing to read a piece by a game developer who agrees that interactive software can tell stories as well or better than other mediums, but that potential for storytelling is being wasted on shallow, linear, overproduced playthings.
The only point of disagreement I have with the author is his praising of the player avatar over the player character. When the protagonist is an avatar of the player, makes decisions based off of the player's history in the player's world, but lives in a separate world... a lot is sacrificed. Avatar characters in games can't undergo complex character development the same way characters in novels and movies can unless the player who is operating the avatar is undergoing development himself. Even in that case, the character development is a result of events that happen in the real world, not the game world. It poses a serious problem for storytellers, I think. More about this when I publish that essay I mentioned.