I have a friend that thinks the Open will be out this weekend for halloween. He thinks since EQ2 is coming out soon and they are admitting a bunch of new testers to Matrix and the Guild Wars thing is happening this weekend that Blizzard will open the beta sign-ups at least on Halloween Day.
I think he might be off a few days as I dont see Blizz starting this on a sunday. If anything it will be a Friday (same day they dropped the open beta soon bomb).