Just got the pre-registration packet in the mail a few days ago. You should be able to register on their website as well. You can register the day of the show too, but I think you get the t-shirts at half price for pre-registering (I could be wrong).
I will be there the weekend (July 17th and 18th), if pinsiders' decide on going. I'm still trying to figure out what time slot I will be working the load-in dock on Friday. I'll have to get one of those "Hi My Name Is..." for pinsiders to find me. I'll be the pinhead getting a chain of free games off of Monster Bash.
Overall, its a great yearly show (pinball & classic-arcade video games on free play). Lots of very tough to find machines ("Medeival Madness", "Cirqus Voltaire", Capcom's "Kingpin" & "Big Bang Bar"). Fun-loving pinheads from all over the west coast to boot. You can't go wrong for the price.