Minecraft RemoteShell V0.45
Connected to console!
01:03:47 [INFO] [VanishNoPacket] meiamone reappeared.
01:03:48 [SEVERE] null
org.bukkit.command.CommandException: Unhandled exception executing command 'vanish' in plugin VanishNoPacket v3.0
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:42)
at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:168)
at org.bukkit.craftbukkit.CraftServer.dispatchCommand(CraftServer.java:386)
at net.minecraft.server.NetServerHandler.handleCommand(NetServerHandler.java:777)
at net.minecraft.server.NetServerHandler.chat(NetServerHandler.java:737)
at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:725)
at org.getspout.spout.SpoutNetServerHandler.a(SpoutNetServerHandler.java:178)
at net.minecraft.server.Packet3Chat.handle(Packet3Chat.java:33)
at net.minecraft.server.NetworkManager.b(NetworkManager.java:226)
at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:100)
at org.getspout.spout.SpoutNetServerHandler.a(SpoutNetServerHandler.java:587)
at net.minecraft.server.NetworkListenThread.a(NetworkListenThread.java:78)
at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:536)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:434)
at net.minecraft.server.ThreadServerApplication.run(SourceFile:465)
Caused by: java.lang.NoSuchMethodError: org.bukkit.entity.Player.canSee(Lorg/bukkit/entity/Player;)Z
at org.kitteh.vanish.VanishManager.toggleVanishQuiet(VanishManager.java:176)
at org.kitteh.vanish.VanishManager.toggleVanish(VanishManager.java:123)
at org.kitteh.vanish.VanishCommand.onCommand(VanishCommand.java:43)
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:40)
... 14 more

As the download page clearly says in huge text, if you wish to use 3.0 you need to have dev build 1871 or higher.