diff --git a/lib/OpenLayers/Layer/SphericalMercator.js b/lib/OpenLayers/Layer/SphericalMercator.js
index 85418fecfa..60092388b9 100644
--- a/lib/OpenLayers/Layer/SphericalMercator.js
+++ b/lib/OpenLayers/Layer/SphericalMercator.js
@@ -186,11 +186,32 @@ OpenLayers.Layer.SphericalMercator = {
 };
 
 /**
- * Note: Two transforms declared
- * Transforms from EPSG:4326 to EPSG:900913 and from EPSG:900913 to EPSG:4326
- *     are set by this class.
+ * Note: Transforms for web mercator <-> EPSG:4326
+ * OpenLayers recognizes EPSG:3857, EPSG:900913, EPSG:102113 and EPSG:102100.
+ * OpenLayers originally started referring to EPSG:900913 as web mercator.
+ * The EPSG has declared EPSG:3857 to be web mercator.  
+ * ArcGIS 10 recognizes the EPSG:3857, EPSG:102113, and EPSG:102100 as 
+ * equivalent.  See http://blogs.esri.com/Dev/blogs/arcgisserver/archive/2009/11/20/ArcGIS-Online-moving-to-Google-_2F00_-Bing-tiling-scheme_3A00_-What-does-this-mean-for-you_3F00_.aspx#12084
  */
-OpenLayers.Projection.addTransform("EPSG:4326", "EPSG:900913",
-    OpenLayers.Layer.SphericalMercator.projectForward);
-OpenLayers.Projection.addTransform("EPSG:900913", "EPSG:4326",
-    OpenLayers.Layer.SphericalMercator.projectInverse);
+(function() {
+    
+    // list of equivalent codes for web mercator
+    var codes = ["EPSG:900913", "EPSG:3857", "EPSG:102113", "EPSG:102100"];
+    
+    var add = OpenLayers.Projection.addTransform;
+    var merc = OpenLayers.Layer.SphericalMercator;
+    var same = OpenLayers.Projection.nullTransform;
+    
+    var i, len, code, other, j;
+    for (i=0, len=codes.length; i<len; ++i) {
+        code = codes[i];
+        add("EPSG:4326", code, merc.projectForward);
+        add(code, "EPSG:4326", merc.projectInverse);
+        for (j=i+1; j<len; ++j) {
+            other = codes[j];
+            add(code, other, same);
+            add(other, code, same);
+        }
+    }
+    
+})();
diff --git a/tests/Layer/SphericalMercator.html b/tests/Layer/SphericalMercator.html
index 460c57ed56..e7202171f1 100644
--- a/tests/Layer/SphericalMercator.html
+++ b/tests/Layer/SphericalMercator.html
@@ -69,7 +69,7 @@
          
         t.eq(strToFixed(point.toString()), 
              strToFixed("POINT(10.000000828446318 20.000000618997227)"), 
-             "point transforms from EPSG:4326 to Spherical Mercator"); 
+             "point transforms from Spherical Mercator to EPSG:4326"); 
     }
     
     function test_SphericalMercator_addTransform(t) {
@@ -88,6 +88,48 @@
              "from EPSG:900913 to EPSG:4326 correctly defined");
     }
     
+    function test_equivalence(t) {
+
+        // list of equivalent codes for web mercator
+        var codes = ["EPSG:900913", "EPSG:3857", "EPSG:102113", "EPSG:102100"];
+        var len = codes.length;
+        
+        t.plan(len + (len * len));
+
+        var ggPoint = new OpenLayers.Geometry.Point(10, 20);
+        var smPoint = new OpenLayers.Geometry.Point(1113195, 2273031);
+        
+        var gg = new OpenLayers.Projection("EPSG:4326");
+        
+        var i, proj, forward, inverse, other, j, equiv;
+        for (i=0, len=codes.length; i<len; ++i) {
+            proj = new OpenLayers.Projection(codes[i]);
+            
+            // confirm that forward/inverse work
+            forward = ggPoint.clone().transform(gg, proj);
+            t.eq(
+                strToFixed(forward.toString()), 
+                strToFixed("POINT(1113194.9077777779 2273030.9266712805)"), 
+                "transforms from EPSG:4326 to " + proj
+            );
+            inverse = smPoint.clone().transform(proj, gg);
+            t.eq(
+                strToFixed(inverse.toString()), 
+                strToFixed("POINT(10.000000828446318 20.000000618997227)"), 
+                "transforms from " + proj + " to EPSG:4326"
+            ); 
+            
+            // confirm that null transform works
+            for (j=i+1; j<len; ++j) {
+                other = new OpenLayers.Projection(codes[j]);
+                equiv = ggPoint.clone().transform(proj, other);
+                t.ok(proj.equals(other),  proj + " and " + other + " are equivalent");
+                t.ok(ggPoint.equals(equiv), "transform from " + proj + " to " + other + " preserves geometry");                
+            }
+        }
+
+    }
+    
   </script> 
 </head>
 <body>