As far I'm concerned if you hack the door and then post about it on the discussion list you are a real Sudoer :-)
We want the doors to be secure, but the goal of door access is to give more people access not to keep anyone out. Obviously that would be a feature of the system at some point, but keeping someone out of the space is more of an organizational question than a technical one.
Theft and vandalism suck, and we want to avoid it, but the truth is that there is no way to really make it 100% impossible for someone to be malicious if they want to. I would hope that sense we run a pretty open space there wouldn't really be a desire to say steal some valuable if they could just come and use it whenever they wanted to. But that's no excuse for poor security, I know..
tl;dr how much security and what kind it's very much an open question.
--Andrew