Well since no one is answering, I thought I'd put my 2 cents in, although some people may disagree there is only one reason (for me anyway) to use boot camp and windows on my 2.4Ghz Macbook Pro = games. I'm quite a (well I like to think I am anyway

) 'hardcore' gamer and have been playing first person shooters since wolfenstein and doom. Windows just has an infinitely bigger (and better) selection of games available (imo).
I've also found that (generally) games run a lot better in windows (partly due to a lot of apple hardware being slightly underclocked (in both of my macbook pro's I've owned anyway) in OS X for (what I assume anyway) heat/noise issues. Also even if a game is ported over to Mac OS X, the performance is usually close to, but rarely equal to the platform it was designed to run on (usually windows).
When getting my macbook pro I really tried to use only OS X games, but when seeing games like Half Life 2, counterstrike source, day of defeat source, supreme commander, oblivion, battlefield 2 etc, and most recently Call of Duty 4 (which 'roxrs my soxrs' by the way), and then comparing the prices of games on windows to the prices on Mac OS X (for those that had Mac OS X ports) I just couldn't justify not using boot camp.
Just last week I was playing Call of Duty 4 online in a particular good game for me (free-for-all, shipment map, and having 76 kills to 19 deaths) people started trash talking Macs and then I was able to say "well... I'm playing on a Mac", the whole room went quiet, then a few others said "me too". It was quite funny and ended up being a good experience as a few of them started asking questions.
Don't get me wrong, Mac OS X is hands down a superior operating system, but when it comes to 'hardcore' games, there's just a much better selection on the dark side.
The beauty is, with an intel Mac I can use Windows for gaming (and gaming only) and Mac OS X for everything else. In a sense, having my cake and eating it too.
Feel free to disagree, let me know your experiences with gaming and the fairer platform, and even throw digital mud at me.
Jay.