2012-02-27 19:57:47 [SEVERE] Error occurred while enabling Vault v1.2.11-b130 (Is it up to date?): org.bukkit.plugin.PluginManager.registerEvents(Lorg/bukkit/event/Listener;Lorg/bukkit/plugin/Plugin;)V
java.lang.NoSuchMethodError: org.bukkit.plugin.PluginManager.registerEvents(Lorg/bukkit/event/Listener;Lorg/bukkit/plugin/Plugin;)V
at net.milkbowl.vault.economy.plugins.Economy_iConomy6.(Economy_iConomy6.java:50)
at net.milkbowl.vault.Vault.loadEconomy(Vault.java:311)
at net.milkbowl.vault.Vault.onEnable(Vault.java:106)
at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:230)
at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:970)
at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:280)
at org.bukkit.craftbukkit.CraftServer.loadPlugin(CraftServer.java:190)
at org.bukkit.craftbukkit.CraftServer.enablePlugins(CraftServer.java:173)
at org.bukkit.craftbukkit.CraftServer.(CraftServer.java:132)
at net.minecraft.server.ServerConfigurationManager.(ServerConfigurationManager.java:52)
at net.minecraft.server.MinecraftServer.init(MinecraftServer.java:147)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:406)
at net.minecraft.server.ThreadServerApplication.run(SourceFile:465)

cause you're using a much outdated CB.