gSyncit is a free, 2-way sync solution for Windows Outlook users. The software does limit you to 365 days in the past and 365 days in the future, but that wouldn't be a deal-breaker for me. The 2-way sync is supported for the default Google Calendar, but you can bring in data from other Google Calendars (i.e., shared calendars) into Outlook using this utility.
If anyone gets the chance to try this with Google Apps Premier, please let me know as this is the kind of solution that is important for users that are married to Outlook and are not interested in web calendaring.
As with all programs of this type, you should probably back up your Outlook calendar and Google Calendar before starting to use it.