diff -r 27b5bd5f0e4c Lib/json/__init__.py
--- a/Lib/json/__init__.py	Sat Sep 01 15:00:34 2012 +0200
+++ b/Lib/json/__init__.py	Sat Sep 01 15:18:54 2012 -0700
@@ -122,7 +122,7 @@
 
 def dump(obj, fp, skipkeys=False, ensure_ascii=True, check_circular=True,
         allow_nan=True, cls=None, indent=None, separators=None,
-        default=None, **kw):
+        default=None, sort_keys=False, **kw):
     """Serialize ``obj`` as a JSON formatted stream to ``fp`` (a
     ``.write()``-supporting file-like object).
 
@@ -155,6 +155,9 @@
     ``default(obj)`` is a function that should return a serializable version
     of obj or raise TypeError. The default simply raises TypeError.
 
+    If *sort_keys* is ``True`` (default ``False``), then the output of dictionaries
+    will be sorted by key.
+
     To use a custom ``JSONEncoder`` subclass (e.g. one that overrides the
     ``.default()`` method to serialize additional types), specify it with
     the ``cls`` kwarg; otherwise ``JSONEncoder`` is used.
@@ -164,7 +167,7 @@
     if (not skipkeys and ensure_ascii and
         check_circular and allow_nan and
         cls is None and indent is None and separators is None and
-        default is None and not kw):
+        default is None and not sort_keys and not kw):
         iterable = _default_encoder.iterencode(obj)
     else:
         if cls is None:
@@ -172,7 +175,7 @@
         iterable = cls(skipkeys=skipkeys, ensure_ascii=ensure_ascii,
             check_circular=check_circular, allow_nan=allow_nan, indent=indent,
             separators=separators,
-            default=default, **kw).iterencode(obj)
+            default=default, sort_keys=sort_keys, **kw).iterencode(obj)
     # could accelerate with writelines in some versions of Python, at
     # a debuggability cost
     for chunk in iterable:
@@ -181,7 +184,7 @@
 
 def dumps(obj, skipkeys=False, ensure_ascii=True, check_circular=True,
         allow_nan=True, cls=None, indent=None, separators=None,
-        default=None, **kw):
+        default=None, sort_keys=False, **kw):
     """Serialize ``obj`` to a JSON formatted ``str``.
 
     If ``skipkeys`` is false then ``dict`` keys that are not basic types
@@ -213,6 +216,9 @@
     ``default(obj)`` is a function that should return a serializable version
     of obj or raise TypeError. The default simply raises TypeError.
 
+    If *sort_keys* is ``True`` (default ``False``), then the output of dictionaries
+    will be sorted by key.
+
     To use a custom ``JSONEncoder`` subclass (e.g. one that overrides the
     ``.default()`` method to serialize additional types), specify it with
     the ``cls`` kwarg; otherwise ``JSONEncoder`` is used.
@@ -222,14 +228,14 @@
     if (not skipkeys and ensure_ascii and
         check_circular and allow_nan and
         cls is None and indent is None and separators is None and
-        default is None and not kw):
+        default is None and not sort_keys and not kw):
         return _default_encoder.encode(obj)
     if cls is None:
         cls = JSONEncoder
     return cls(
         skipkeys=skipkeys, ensure_ascii=ensure_ascii,
         check_circular=check_circular, allow_nan=allow_nan, indent=indent,
-        separators=separators, default=default,
+        separators=separators, default=default, sort_keys=sort_keys,
         **kw).encode(obj)