Index: src/java/com/thoughtworks/xstream/XStream.java
===================================================================
--- src/java/com/thoughtworks/xstream/XStream.java	(revision 1691)
+++ src/java/com/thoughtworks/xstream/XStream.java	(working copy)
@@ -638,7 +638,11 @@
         registerConverter(new MapConverter(mapper), PRIORITY_NORMAL);
         registerConverter(new TreeMapConverter(mapper), PRIORITY_NORMAL);
         registerConverter(new TreeSetConverter(mapper), PRIORITY_NORMAL);
-        registerConverter(new PropertiesConverter(), PRIORITY_NORMAL);
+        
+        if (!jvm.isAppEngine()) {
+        	registerConverter(new PropertiesConverter(), PRIORITY_NORMAL);
+        }
+        
         registerConverter(new EncodedByteArrayConverter(), PRIORITY_NORMAL);
 
         registerConverter(new FileConverter(), PRIORITY_NORMAL);
@@ -696,12 +700,16 @@
             dynamicallyRegisterConverter(
                 "com.thoughtworks.xstream.converters.enums.EnumConverter", PRIORITY_NORMAL,
                 null, null);
-            dynamicallyRegisterConverter(
-                "com.thoughtworks.xstream.converters.enums.EnumSetConverter", PRIORITY_NORMAL,
-                new Class[]{Mapper.class}, new Object[]{mapper});
-            dynamicallyRegisterConverter(
-                "com.thoughtworks.xstream.converters.enums.EnumMapConverter", PRIORITY_NORMAL,
-                new Class[]{Mapper.class}, new Object[]{mapper});
+            
+            if (!jvm.isAppEngine()) {
+	            dynamicallyRegisterConverter(
+	                "com.thoughtworks.xstream.converters.enums.EnumSetConverter", PRIORITY_NORMAL,
+	                new Class[]{Mapper.class}, new Object[]{mapper});
+	            dynamicallyRegisterConverter(
+	                    "com.thoughtworks.xstream.converters.enums.EnumMapConverter", PRIORITY_NORMAL,
+	                    new Class[]{Mapper.class}, new Object[]{mapper});
+            }
+            
             dynamicallyRegisterConverter(
                 "com.thoughtworks.xstream.converters.basic.StringBuilderConverter",
                 PRIORITY_NORMAL, null, null);
Index: src/java/com/thoughtworks/xstream/core/JVM.java
===================================================================
--- src/java/com/thoughtworks/xstream/core/JVM.java	(revision 1691)
+++ src/java/com/thoughtworks/xstream/core/JVM.java	(working copy)
@@ -26,9 +26,10 @@
     private ReflectionProvider reflectionProvider;
     private transient Map loaderCache = new HashMap();
     
-    private final boolean supportsAWT = loadClass("java.awt.Color") != null;
-    private final boolean supportsSwing = loadClass("javax.swing.LookAndFeel") != null;
-    private final boolean supportsSQL = loadClass("java.sql.Date") != null; 
+    private final boolean isAppEngine = loadClass("com.google.appengine.api.datastore.DatastoreService") != null;
+    private final boolean supportsAWT = (loadClass("java.awt.Color") != null) && (!isAppEngine);
+    private final boolean supportsSwing = (loadClass("javax.swing.LookAndFeel") != null) && (!isAppEngine);
+    private final boolean supportsSQL = loadClass("java.sql.Date") != null;
 
     private static final String vendor = System.getProperty("java.vm.vendor");
     private static final float majorJavaVersion = getMajorJavaVersion();
@@ -63,6 +64,10 @@
         return majorJavaVersion >= 1.6f;
     }
 
+    public boolean isAppEngine() {
+        return isAppEngine;
+    }
+
     private static boolean isSun() {
         return vendor.indexOf("Sun") != -1;
     }
@@ -185,7 +190,7 @@
         return reflectionProvider;
     }
 
-    private boolean canUseSun14ReflectionProvider() {
+    public boolean canUseSun14ReflectionProvider() {
         return (isSun()
             || isApple()
             || isHPUX()
@@ -196,6 +201,7 @@
             || isSAP() 
             || isDiablo())
             && is14()
+            && (!isAppEngine())
             && loadClass("sun.misc.Unsafe") != null;
     }
 
@@ -262,5 +268,6 @@
         System.out.println("Supports Swing: " + jvm.supportsSwing());
         System.out.println("Supports SQL: " + jvm.supportsSQL());
         System.out.println("Reverse field order detected (may have failed): " + reverse);
+        System.out.println("Google App Engine: " + jvm.isAppEngine());
     }
 }