None of the midnight Star Wars shows have sold out in the past, though some guy brought a lawnchair to the theater last time and "camped out" ... at 11:45 PM, just so it could be said that *someone* in the town camped out for Star Wars.
So anyway, that's my plan for seeing Revenge of the Sith next month ... I'll buy my tickets at 4:00 PM that day and I'll show up at the theater 15 minutes ahead of time. No fuss, no muss, no advance tickets required.