SidedProxy now has sensible default values - nested ClientProxy and ServerProxy classes.

src/main/java/net/minecraftforge/fml/common/ProxyInjector.java

@@ -57,6 +57,10 @@ public class ProxyInjector
                     continue;
                 }
                 String targetType = side.isClient() ? annotation.clientSide() : annotation.serverSide();
+                if(targetType.equals(""))
+                {
+                    targetType = targ.getClassName() + (side.isClient() ? "$ClientProxy" : "$ServerProxy");
+                }
                 Object proxy=Class.forName(targetType, true, mcl).newInstance();
 
                 if (languageAdapter.supportsStatics() && (target.getModifiers() & Modifier.STATIC) == 0 )

src/main/java/net/minecraftforge/fml/common/SidedProxy.java

@@ -50,12 +50,14 @@ import java.lang.annotation.Target;
 public @interface SidedProxy
 {
     /**
-     * The name of the client side class to load and populate
+     * The full name of the client side class to load and populate.
+     * Defaults to the nested class named "ClientProxy" in the current class.
      */
     String clientSide() default "";
 
     /**
-     * The name of the server side class to load and populate
+     * The full name of the server side class to load and populate.
+     * Defaults to the nested class named "ServerProxy" in the current class.
      */
     String serverSide() default "";