mChatSuite is very popular http://dev.bukkit.org/server-mods/mchat/files/ so please add this integration

What sort of integration?

hide from /list, use custom mchatsuts join/left messages
http://dev.bukkit.org/server-mods/mchat/tickets/150-list-displays-players-who-are-invisible/#c1

With the Bukkit visibility API, plugin developers should be encorporating player.canSee(otherplayer) checks into their /list code. As for custom join/left messages, what is special about mchatsuite messages that can't be done with the existing custom fake join/quit message system?

k, i've opened a ticket there, maybe this time it won't bounce :)
as for the join/left messages i wanted to say http://dev.bukkit.org/server-mods/mchat/pages/current-variables/ but i don't really know if they work in those messages... but >if there would be an integration< it seams reasonable that vanish should use them :)

but if developers use "player.canSee(otherplayer)" whats exactly the integration with Essentials?

The essentials integration is from before the bukkit api existed. And currently essentials hasn't updated to use canSee, so I've left it in.

He added it in :)