The new scoreboard system in Minecraft 1.5 would be a great way to display vanish status! Nothing when visible, and a 'Vanished' display on the player's scoreboard when vanished.

Thanks!

Keep in mind that scoreboards are one per user and pretty much one plugin should touch per server. I may still add this but it would be disabled in config by default. Waiting on bukkit for api

Not planning to add at this time.