New bpy method for World module to set World for current scene:

my_world.makeActive()

Contributed by Campbell Barton (ideasman)

source/blender/python/api2_2x/World.c

@@ -680,6 +680,21 @@ static PyObject *World_getScriptLinks (BPy_World *self, PyObject *args)
 }
 
 
+
+/* world.makeActive */
+static PyObject *World_makeActive (BPy_World *self)
+{
+	World *world = self->world;
+	/* If there is a world then it now has one less user */
+	if( G.scene->world) 
+		G.scene->world->id.us--;
+	world->id.us++;
+	G.scene->world = world;
+	Py_INCREF(Py_None);
+	return Py_None;
+}
+
+
 /*@{*/
 
 /**

source/blender/python/api2_2x/doc/World.py

@@ -314,3 +314,10 @@ class World:
     @type event: string
     @param event: "FrameChanged" or "Redraw".
     """
+  
+  def makeActive ():
+    """
+    Make this world active in the current scene.
+    @rtype: PyNone
+    @return:  PyNone    
+    """