[Tyhm]

Another half-baked security suggestion that may already be implemented:
Allow the serveroptions to determine what data is sent from player to player. For instance, there might be a server where the player's X, Y, and level ought not be visible - for instance, a Ninja server where hiding is everything - if such data was being sent and the client's system was set to ignore it, it'd be trivial for some trainer somewhere to override that and make some clientside script to draw a big bullseye on the erstwhile rogue...but if the Server says the victim's under no obligation to tell the hacker where he is, the hacker never recieves the packet saying "You are in level13.graal. Victim is in level13.graal, at (32,32), using walk.gani, has a head0.png, his colors are red/green/blue/black/white..." in the first place.
Counter problem - hackers could then refuse to send packets, I suppose.
Solution - the server checks every once in a while. "Victim, did you see Hacker while you were in level13? No? Hmm, bump him up a threat level..."