Wired magazine have a great article entitled "Halo 3: How Microsoft Labs Invented a New Science of Play". If you have played Halo, and are looking forward to the release of Halo 3, then this is a 'must read' article.
If you work in software development world, its very interesting for another reason - they way Bungie approach QA and testing:
"After each session Pagulayan analyzes the data for patterns that he can report to Bungie. For example, he produces snapshots of where players are located in the game at various points in time — five minutes in, one hour in, eight hours in — to show how they are advancing. If they're going too fast, the game might be too easy; too slow, and it might be too hard. He can also generate a map showing where people are dying, to identify any topographical features that might be making a battle onerous. And he can produce charts that detail how players died, which might indicate that a particular alien or gun is proving unexpectedly lethal or wankishly impotent."
Yes, its only a game, but if more companies adopted a more rigorous and imaginative approach to testing their software, we would all benefit. So read the article, and think about your own testing procedures.