In the end, the GM actually ended up placing a warning on the guild leader's account for performing illegal gambling.
My take on this? Blizzard is making a mistake. As much as I despised the casinos that were available early in the game and was extremely pleased to see them go, I think Blizzard is significantly over-reacting to this guild's attempts to make the new game content more interesting. While their raffle may be able to be defined as gambling by its literal definition, I really don't see a problem with how they're running the raffle. It's helping their server achieve a goal, providing a better incentive to participate in the War Effort, and increasing teamwork on the server--something that'll be sorely needed once the Gates are opened.
There's still no official word from Blizzard (a blue post), but I'll be eagerly watching this thread for an explanation (or apology?).