(There are no spoilers in this post-- see note below.)
We've been trying to stay away from covering the specifics of this, but I'm pretty sure that by now, everyone who wanted to read Harry Potter's last book spoiler-free has done so (I finished it last Saturday night after a marathon reading session, and really enjoyed it). So perhaps now's the time to, as Terra Nova does, examine these strange relationships between virtual worlds.
Why would the WoW forums (or any MMORPG forums, as TN mentions FFXI) be a hotbed of spoiler posting, and not, say, a note posted on the door of a bookstore (or any other place that is likely to hit more Harry Potter fans than the forums)? What is it that attracts the WoW playership to be both inclined to post spoilers, and inclined to be bothered by them?
The answer, I think, lies in the fact that WoW really has two audiences-- there are gamers, like myself, who also play Halo and Counterstrike. They play games to get the highest level and the best gear and most Arena points, and they think the Harry Potter books are nothing more than kids' books about a stupid wizard school. These are the people who think it's funny to post spoilers on a forum, and who take pleasure in ruining someone else's appreciation of something they have no appreciation for. But there's a second group that also plays WoW, and they are very different.
*Note: Before you go any further, I should mention that if you haven't read the Harry Potter books yet, you may want to stay away from the comments on this post. Spoilers will be deleted from our comments, but we can only act so fast, and any post about spoilers is bound to attract some itself.