|Perl: the Markov chain saw|
Most of what I'm saying has already been said better by others.
Multi-login: I agree with kudra that multi-logins is wrong, but it's difficult at best to enforce. Multiple people from one location and people with multiple IPs are both fairly common.
Chatbox: Prohibiting logging of chatbox is hard to do. As long as the guideline says that the contents of the chatbox can not be used, that should offer as much protection as can be had.
Profanity: Depends on the context, but I would say any directed at people shouldn't be done. That goes with the anti-assault clause as well, but can be subjective. Except for certain posts as ovid pointed out.
Voting and experience: I said this a different node, but I think a karma system would be good. If you -- more than you ++ in a day, you may lose experience.
Published source: Tough one. Easily identified code should be sited, but I'm pretty sure a lot of people have snippits of code in their head that other people have used or even been published. Before File::Find, I had a directory walker that probably looks similar to what other people would throw together.
Enforcement: Since none of this is really enforceable, we can have the guidelines (Off the FAQ?) published and when someone trangresses send them there as vroom suggests. Otherwise, it seems self correcting.
I've learned a lot from the short time I've been at perlmonks and the sense of community is something I hadn't seen since I was involved on a forum in the early 80's. Thank you vroom and everyone else.