I finally got tired of fighting with Linuxworld's Website for online registration--it was quite willing to tell me that I had to fill out all the forms, but not to present any of them--and emailed the contact person. She sent me a phone number to call for help. Reasonable, except that if I wanted to register by phone, I could have done it at any time.
So while I was feeling vaguely annoyed, the day's mail landed on my desk. The first item was a nice laminated exhibits pass--all I want, and the only part that's free--with a note saying, basically, that since email hadn't convinced me to sign up, they'd done it for me. The second was a card from an exhibitor, which I, or anyone, can trade in for a pass to the exhibits. Procrastination pays.