--- Zope2/Startup/zopeschema.xml.orig	2009-05-20 10:09:56.000000000 +0200
+++ Zope2/Startup/zopeschema.xml	2009-05-20 09:02:27.000000000 +0200
@@ -444,6 +444,14 @@
     <metadefault>us</metadefault>
   </key>
 
+  <key name="datetime-default-localtimezone" datatype="boolean" default="off">
+    <description>
+     By default datetime uses the UTC timezone if no timezone is given. 
+     Set this option to on to use system local time zone as default time zone. 
+    </description>
+    <metadefault>off</metadefault>
+  </key>
+
   <key name="zserver-threads" datatype="integer" default="4">
      <description>
      Specify the number of threads that Zope's ZServer web server will use
--- DateTime/DateTime.py.orig	2009-05-20 09:09:32.000000000 +0200
+++ DateTime/DateTime.py	2009-05-20 10:12:07.000000000 +0200
@@ -16,13 +16,14 @@
 
 
 import re, math,  DateTimeZone
-from time import time, gmtime, localtime
+from time import time, gmtime, localtime, strptime, mktime
 from time import daylight, timezone, altzone, strftime
 from datetime import datetime
 from interfaces import IDateTime
 from interfaces import DateTimeError, SyntaxError, DateError, TimeError
 from zope.interface import implements
 from pytz_support import PytzCache
+from App.config import getConfiguration
 _cache = PytzCache
 
 default_datefmt = None
@@ -31,7 +32,6 @@
     global default_datefmt
     if default_datefmt is None:
         try:
-            from App.config import getConfiguration
             default_datefmt = getConfiguration().datetime_format
             return default_datefmt
         except:
@@ -1805,10 +1805,14 @@
         if fields['signal'] or fields['Z']:
             tznaive = False
         else:
-            tznaive = True
+            if getConfiguration().datetime_default_localtimezone :
+                dtstr = "%04.4d-%02.2d-%02.2d %02.2d:%02.2d:%02.2d" % (year, month, day, hour, minute, seconds)
+                dsttime = strptime(dtstr, "%Y-%m-%d %H:%M:%S")
+                dsdtime = localtime(mktime(dsttime))
+                ltzoff =  _tzoffset(self.localZone(dsdtime), None)
+                hour_off = ltzoff / 3600
+                min_off = (ltzoff % 3600) / 60
         
-        # Differ from the specification here. To preserve backwards
-        # compatibility assume a default timezone == UTC.
         tz = 'GMT%+03d%02d' % (hour_off, min_off)
 
         return year, month, day, hour, minute, seconds, tz, tznaive