Actually this year we're tightening up security a bit.
Please don't just show up. It's very nice of Stanford to lend us the auditorium, and we don't want to be bad citizens. If we have too many people for the room, the campus police won't like it.
last time I went (in 2005), there was absolutely no security and plenty of free chairs. Anyone could've easily shown up without being questioned...
I don't know if it will be the same this year, but if you're in the area maybe you can try showing up?
Who knows... if they catch you... maybe PG will appreciate your hacker-ish persistence :)