You can only sync your default Google calendar to Outlook calendar using Google Calendar Sync, but you want to sync ALL your calendars.

The Not-quite Solution:

The easiest way is to merge all your Google calendars into your default Google calendar, but then you lose the pretty colors and Google is likely to release an update in the future that will make this entire article moot. The goal here is a temporary solution that is completely reversible and merging your calendars is not reversible.

Solution:

The following steps assume your default Google calendar is labeled ‘Personal’ and you have additional calendars you would like to sync.

1. Configure Google Calendar
   1. Rename your ‘Personal’ calendar ‘All’
   2. Create a new calendar called ‘Personal’ and move all events from ‘All’ to ‘Personal’
   3. Hide all calendars except ‘All’
2. Configure your PC
   1. Install RemoteCalendars (Outlook plugin for iCal support)
   2. For each Google calendar except ‘All’, copy the iCal private url from Google Calendar into RemoteCalendars in Outlook (Do not copy you default calendar, labeled ‘All’, or you’ll create a ton of duplicates)
   3. Install Google Calendar Sync and set it to sync 2-way
      

When your done your sync flow should look like this:

• iTunes will grab changes you made on your iPhone and add them to Outlook
• Outlook will grab changes you made on Google Calendars
• Google Calendar Sync will push all changes to Google Calendars
• iTunes will push all changes to iPhone

The Catch:

If you add/edit an event in the ‘All’ calendar on Google Calendars, it won’t get synced. So you’ll need to remember to always add events to calendars other than ‘All’. Remember, the idea here is to maintain separate calendars until Google releases a Calendar Sync version that supports multiple calendars.

UPDATE (October 2nd, 2008)

Apple recently released iPhone 2.0 software which sinces multiple calendars using either Microsoft Exchange of Apple’s MobileMe.

UPDATE (February 18, 2009)

Google launched Google Sync for the iPhone.  Now you can sync multiple calendars and contacts via Microsoft’s ActiveSync protocol.  Granted it’s in beta and can’t sync your mail yet, but it’s the solution I’ve been waiting for.  Finally.

I may be the only person who has ever had this problem, but if you use ZoneAlarm as a firewall, it can prevent your iPhone from syncing with iTunes. It can even prevent iTunes from recognizing that your iPhone is plugged in.

Solution:

The only solution I could find was to disable program control. However, this could potentially allow malicious programs to send and receive data. Assuming you use a good anti-virus solution (I recommend avast), you shouldn’t need to worry about getting malicous programs in the first place. However, I went ahead and enabled the default windows firewall to be safe.