I like the sound of that

I saw a server the other day which was on what they called "Extreme" mode which has PvP on etc. - I hadn't really thought about it until then, but that sounds awesome! I imagine it would add a level of tension while you mine and build, always looking over your shoulder incase someone is spying on you ready to kill you and take your goods
Plus, people would have to think about their builds differently (I.e. add traps, make places more secure). Every-man(or zumi)-for-him(her)self mode