Blizzard just announced in the forums that tickets for BlizzCon 2007 (Anaheim, August 3 and 4) are now available to purchase, for $100. There are a mere 51 days left until the festival of all things Blizzard, so if you want to go, you should probably get on it. Last year's sold out, I think. You can buy up to 5 tickets per billing address if you want to bring the whole household.
I'm sure all sorts of cool stuff will be given to attendees; so far, we know that the swag will include a beta pass to "an upcoming Blizzard game" (I support Dan's guess that it's StarCraft 2) and an in-game murloc suit for one of your characters. So who's going to be going? WoW Insider will be there in force for sure.