Index: django/contrib/formtools/preview.py
===================================================================
--- django/contrib/formtools/preview.py	(revision 5319)
+++ django/contrib/formtools/preview.py	(working copy)
@@ -91,7 +91,7 @@
 
     def preview_get(self, request):
         "Displays the form"
-        f = self.form(auto_id=AUTO_ID)
+        f = self.form(auto_id=AUTO_ID, initial=self.initial(request))
         return render_to_response(self.form_template,
             {'form': f, 'stage_field': self.unused_name('stage'), 'state': self.state},
             context_instance=RequestContext(request))
@@ -121,6 +121,15 @@
 
     # METHODS SUBCLASSES MIGHT OVERRIDE IF APPROPRIATE ########################
 
+    def initial(self, request):
+        """
+        Returns dynamic initial values for the given Form instance.
+        
+        The return value should be a dictionary mapping field names to 
+        initial values.
+        """
+        return None
+
     def parse_params(self, *args, **kwargs):
         """
         Given captured args and kwargs from the URLconf, saves something in