diff --git a/doc/build.xml b/doc/build.xml
index 74bc02b..068a1a7 100644
--- a/doc/build.xml
+++ b/doc/build.xml
@@ -10,7 +10,7 @@
 	<property.ensure name="gwt.dev.jar" location="${gwt.build.lib}/gwt-dev-linux.jar" />
 
 	<property name="USER_PKGS" value="com.google.gwt.core.client;com.google.gwt.core.ext;com.google.gwt.core.ext.typeinfo;com.google.gwt.i18n.client;com.google.gwt.json.client;com.google.gwt.junit.client;com.google.gwt.user.client;com.google.gwt.user.client.rpc;com.google.gwt.user.client.ui;com.google.gwt.user.server.rpc;com.google.gwt.xml.client;com.google.gwt.http.client;com.google.gwt.junit.viewer.client" />
-	<property name="LANG_PKGS" value="java.lang;java.util" />
+	<property name="LANG_PKGS" value="java.lang;java.util;java.io" />
 	<property name="DOC_PKGS" value="com.google.gwt.doc" />
 
 	<!--
diff --git a/user/src/com/google/gwt/user/client/rpc/IsSerializable.java b/user/src/com/google/gwt/user/client/rpc/IsSerializable.java
index e04bc32..7a9c493 100644
--- a/user/src/com/google/gwt/user/client/rpc/IsSerializable.java
+++ b/user/src/com/google/gwt/user/client/rpc/IsSerializable.java
@@ -15,8 +15,14 @@
  */
 package com.google.gwt.user.client.rpc;
 
+import java.io.Serializable;
+
 /**
- * Marker interface used to indicate a family of classes is serializable.
+ * Marker interface indicating that a type is intended to be used with a
+ * {@link RemoteService}. Do not confuse this interface with
+ * {@link Serializable java.io.Serializable}, which is included in the GWT JRE
+ * Emulation Library for source compatibility only and which will not by itself
+ * make a class usable with a {@link RemoteService}.
  */
 public interface IsSerializable {
 }
diff --git a/user/super/com/google/gwt/emul/java/io/Serializable.java b/user/super/com/google/gwt/emul/java/io/Serializable.java
new file mode 100644
index 0000000..1b0bd11
--- /dev/null
+++ b/user/super/com/google/gwt/emul/java/io/Serializable.java
@@ -0,0 +1,27 @@
+/*
+ * Copyright 2007 Google Inc.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ * 
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package java.io;
+
+import com.google.gwt.user.client.rpc.IsSerializable;
+import com.google.gwt.user.client.rpc.RemoteService;
+
+/**
+ * Provided for source compatibility only; implementing
+ * <code>java.io.Serializable</code> is not a substitute for
+ * {@link IsSerializable} for use with a {@link RemoteService}.
+ */
+public interface Serializable {
+}