Frasca over at talks about the narratology / ludology debate. I think this is an interesting classification (admittedly because I think I can make a clever point, or would be able to if I were to sit down and write it).

If that didn’t scare you, I recommend this article by Henry Jenkins, which mentions this debate but then proposes an alternative way of looking at things which he calls environmental storytelling. Although I have an altogether different perspective on this, I recommend the article.