Ann Otoole over on SLU posted up a snapshot of one of the best privacy options ever introduced into Second Life. Basically you can set it so nobody outside of your parcel can see or chat with residents in your parcel (I'm sure IM's will still go through though). This is currently only on the official viewer from Linden Labs but I'm pretty sure we'll see it on third party viewers pretty soon.
Now my question would be this; how well does this work against chat spies? Those things that work from the other side of the sim and record anything said in local. If they keep those from listening in then this thing is a godsend for privacy in Second Life.
Anyways, here is Ann's screenshot showing where it's at in the land controls.