I spoke with MiracleMan and he said it looks like SimpleClans hasn't updated to the new mChat API.

Please resolve. So much log spam (I can deal with the -clan instead of the clan tag), but the errors are annoying. Unfortunately, I've hit the waterfall when updating plugins... the latest Vault needs the latest mChat, which needs the latest SimpleClans. I'll back out the change, but this is going to put me fairly behind on keeping up to date with things. <- (This is my whiny admin justification). Thanks for all your help :)

2012-04-13 10:09:40 [SEVERE] Could not pass event PlayerChatEvent to SimpleClans
org.bukkit.event.EventException
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:303)
at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
at org.bukkit.plugin.TimedRegisteredListener.callEvent(TimedRegisteredListener.java:30)
at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:459)
at net.minecraft.server.NetServerHandler.chat(NetServerHandler.java:786)
at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:764)
at net.minecraft.server.Packet3Chat.handle(Packet3Chat.java:34)
at net.minecraft.server.NetworkManager.b(NetworkManager.java:229)
at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:113)
at net.minecraft.server.NetworkListenThread.a(NetworkListenThread.java:78)
at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:551)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:449)
at net.minecraft.server.ThreadServerApplication.run(SourceFile:492)
Caused by: java.lang.NoSuchMethodError: in.mDev.MiracleM4n.mChatSuite.mChatSuite.getAPI()Lin/mDev/MiracleM4n/mChatSuite/api/mChatAPI;
at net.sacredlabyrinth.phaed.simpleclans.managers.PermissionsManager.addSetMChatClanTag(PermissionsManager.java:147)
at net.sacredlabyrinth.phaed.simpleclans.managers.ClanManager.updateDisplayName(ClanManager.java:289)
at net.sacredlabyrinth.phaed.simpleclans.listeners.SCPlayerListener.onPlayerChat(SCPlayerListener.java:264)
at sun.reflect.GeneratedMethodAccessor232.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:301)
... 12 more