PVPStatus

Type /pvpstatus in the chat. It will bring up a window that shows the PvP status for every raid member (on or off).

In TBC, there is currently a bug where buffs and debuffs are not properly applied in a raid setup. If the majority of the group has /pvp set to the same status (on or off), it will work correctly.

There is also a Whisper button on the same line as a player who has PvP off. Clicking it once will open the whisper window, and clicking it again will paste the message to the player. This way, you can let people know if they need to type /pvp to receive all buffs in the raid.

It also checks whether they have the "Sated" debuff before pulling the boss.