Totally out of date. Hug me and I'll might update it.
This addon will hide/show player names (and guild name/rank etc) based on the PvP'ishness of the zone you're currently in. Typically, in cities and noob areas and instances, player names will not show. In contested/hostile areas and battlegrounds, tough, player names will appear.
I made this addon as I found it annoying to go trough the interface options menu all the time. Basically, I didn't want to play with player names in instances/cities, as I think it looks stupid and fills the screen with unneeded info. When PvP'ing, tough, having player names enabled is crusial to easily spot wether or not the player is in the opposing faction.
It works in wow 2.0 as well, but does not work very good on PvE servers.