Index: django/http/__init__.py
===================================================================
--- django/http/__init__.py	(revision 7145)
+++ django/http/__init__.py	(working copy)
@@ -79,6 +79,9 @@
 
     def is_secure(self):
         return os.environ.get("HTTPS") == "on"
+    
+    def is_ajax(self):
+        return self.META.get('HTTP_X_REQUESTED_WITH') == 'XMLHttpRequest'
 
     def _set_encoding(self, val):
         """
Index: docs/request_response.txt
===================================================================
--- docs/request_response.txt	(revision 7145)
+++ docs/request_response.txt	(working copy)
@@ -189,6 +189,23 @@
    Returns ``True`` if the request is secure; that is, if it was made with
    HTTPS.
 
+``is_ajax()``
+   **New in Django development version**
+
+   Returns ``True`` if the request was made via an XMLHttpRequest by checking 
+   the 'HTTP_X_REQUESTED_WITH' header for the string 'XMLHttpRequest'. The 
+   following major Javascript libraries send this header:
+
+   * jQuery
+   * Dojo
+   * MochiKit
+   * MooTools
+   * Prototype
+   * YUI
+   
+   If you write your own XMLHttpRequest, you will have to set this header 
+   manually to use this method.
+
 QueryDict objects
 -----------------