Google apps is now offering sync for Microsoft Outlook, including email, contacts and calendar.
Sync for Microsoft Outlook is an Outlook Plugin for Outlook 2003 and 2007. Your email, contacts and calendar are synched seamlessly with your Google Apps accounts. This allows you to access the same secure information from either Outlook or the Google Apps interface. Importing your existing data from Exchange is easy, too, so you’ll waste no time in making the transition.
Google apps, Sync for Microsoft Outlook