All code to call events and delegate back to plugins

src/org/bukkit/event/player/PlayerEvent.java

@@ -16,7 +16,25 @@ public abstract class PlayerEvent extends Event {
         player = who;
     }
 
+    /**
+     * Returns the player involved in this event
+     * @return Player who is involved in this event
+     */
     public final Player getPlayer() {
         return player;
     }
+
+    /**
+     * Represents the different types of events
+     */
+    public enum EventType {
+        /**
+         * A player joins a server
+         */
+        Join,
+        /**
+         * A player leaves a server
+         */
+        Quit
+    }
 }

src/org/bukkit/event/player/PlayerListener.java

@@ -1,13 +1,24 @@
 
 package org.bukkit.event.player;
 
+import org.bukkit.event.Listener;
+
 /**
  * Handles all events thrown in relation to a Player
  */
-public abstract class PlayerListener {
+public abstract class PlayerListener implements Listener {
     private PlayerListener() {
     }
 
+    /**
+     * Called when a player joins a server
+     * @param event Relevant event details
+     */
     public abstract void onPlayerJoin(PlayerJoinEvent event);
+
+    /**
+     * Called when a player leaves a server
+     * @param event Relevant event details
+     */
     public abstract void onPlayerQuit(PlayerQuitEvent event);
 }