I was surfing around Google apps stumbled across Google Calendar Sync, what is does is it syncs events between Google Calendar and Microsoft Outlook Calendar.
Keep in mind that it’s not possible to sync events on secondary calendars at this time. Google Calendar Sync will only sync events from your primary Google Calendar and your default Microsoft Outlook calendar.
I think it should work with Google Apps and Hosted domains… I am not sure on that so I got to check it out myself…
See the following URL for more info… http://www.google.com/support/calendar/bin/answer.py?answer=89955

