I’ve been asked this question a few times recently… “Is there a good way to sync Goolge Calendar to Outlook on a Mac?”.
In order for Outlook to sync to Google calendar, it must support MAPI.
On the Windows side, you can install Google Apps Sync for Microsoft Outlook, which is a plug-in that gives Windows Outlook MAPI support, therefore allowing it to sync Google calendars.
MAPI support doesn’t exist with Mac Outlook (yet). Although you can setup Mac Outlook with a Google account via IMAP to send/receive email, it doesn’t allow directly syncing the Google calendar or contacts.
One work around is to sync Apple’s iCal to Google calendar, then maintain a constant sync between iCal and Outlook, but the process is complex and kludgy (plus easily broken). Another workaround was to use a third-party app named Spanning Sync, but it has been discontinued and you can no longer buy/renew subscriptions. Some people that were using Spanning Sync have migrated to BusyCal, but it has proven unreliable with OS X 10.7 and 10.8 due to bugs with Apple’s Sync Services.
So the answer is… there is no good way currently to sync Google calendar to Outlook on a Mac.
In my opinion, Mac-centric clients that want to use Google Apps for mail/contacts/calendars, would be best off using Google’s web interface (accessed via Chrome). Alternatively, Apple’s native communication apps (Mail, Address Book, Contacts, iCal, Calendar) will sync with Google Apps… and they work fairly well.