Why not pull a George Costanza. Walk in to the Guthrie Theater as if you're all registered and everything.
Then when someone tells you that you're on the waiting list, clench your shirt and scream out "It's happening" (ie: fake heart attack; drop your glasses while you're at it for dramatic effect).
In theory that should result in a JAMF employee giving you a badge and sending you on your way.
Don, you took the words out of my brain. Thats exactly what I would do. Worst case scenario, you got yourself a little vacation in the Twin Cities. Do the Purple Rain tour, drink some beers, and watch the JNUC videos when they are posted online.
I can't say that I've never just walked into a free conference that I've not registered for. I'm not sure I'd bank a flight and hotel stay on it though. That said, if you pull any of the above mentioned ploys, I'll assist in any way I can!