Index: Lib/test/test_datetime.py
===================================================================
--- Lib/test/test_datetime.py	(revision 78559)
+++ Lib/test/test_datetime.py	(working copy)
@@ -1130,6 +1130,10 @@
 class SubclassDatetime(datetime):
     sub_var = 1
 
+class AlwaysEqual(object):
+    def __eq__(self, other):
+        return True
+
 class TestDateTime(TestDate):
 
     theclass = datetime
@@ -1455,6 +1459,17 @@
             self.assertEqual(cmp(t2, t1), 1)
 
 
+    # tests that datetime returns NotImplemented
+    def test_foreign_compare(self):
+        args = [2010, 1, 1]
+        d1 = self.theclass(*args)
+        
+        test_comparable = AlwaysEqual()
+
+        self.assertTrue(test_comparable == d1)
+        self.assertTrue(d1 == test_comparable)
+
+
     # A helper for timestamp constructor tests.
     def verify_field_equality(self, expected, got):
         self.assertEqual(expected.tm_year, got.year)