I had originally come up with this solution for syncing my Google Calendars with Windows Phone. It turns out the PlayBook needs the same workaround in order to sync multiple Google Calendars using Exchange ActiveSync. (Thanks, Adam, for pointing this out in the comments!) The steps are almost identical to the Windows Phone solution…

The Solution in a Nutshell

Google provides a web page for selecting which of your calendars to sync, but they only made the page visible to iOS devices (also Android and, more recently, Windows Phone). The basic idea is to make Google think you’re browsing to that page on an iOS device (iPhone, iPad, iPod Touch) so that you can select additional calendars to sync to your PlayBook. There are 2 ways of doing this: actually using an iOS device if you have access to one, or spoofing the user agent of your web browser to make Google think you’re on iOS. I’ll be detailing the latter approach.

There is one additional workaround before we’re able to select additional calendars; that’s because Google knows we’re trying to sync with a PlayBook and don’t allow us to select any calendars. Luckily, Google uses JavaScript as the only mechanism to prevent us from selecting more. So while the web developers among us are shaking their heads in disbelief at Google for using this web programming practice from 1996, this is great news for us because all we have to do to get around the limitation is to disable JavaScript.

The Details

(Before proceeding, please note that I assume you’ve already added your Google account to your PlayBook running OS 2.0 and you have synced your Google Calendar to it.)

I’ll use desktop Safari for this example because it has an inherent way to changing the user agent string. But most browsers can do this, sometimes using an addon or an extension.

1. Install Safari if you don’t have it.
2. Open Safari, go to the Preferences window, then go to the Advanced tab. There should be a setting called “Show Develop menu in menu bar”. Check that. Close the Preferences window.
   
3. Now locate the Develop menu you just enabled. Under “User Agent”, select any of the iOS devices. Web sites will now see your browser as the device you chose.
   
4. Go to google.com and log into your Google account.
5. Now open this URL: http://m.google.com/sync. You should see a list of devices you have syncing with the account, and one of them should be your PlayBook. (Note that you will only be shown this page if you’ve changed your user agent correctly and you’re already logged in)
   
6. Go to the Preferences window again, this time to the Security tab. Disable JavaScript and close the window.
   
7. Now click on the entry for your Playbook. Chances are that you won’t see any calendars listed. Check the URL of the page and see if it ends in “&supportMultiCalendars=false”. Change the false to true and press Enter to load the page again. 
8. You should now be presented with a list of all your calendars (personal, subscribed, and Google-provided ones like holidays).
   
9. Because JavaScript is disabled, you’ll be able to select additional calendars and click Save.
10. You are done. Go to Calendar app on your PlayBook and resync. Your calendars should show up within minutes, but it may take several hours for your calendar events to appear.
11. Don’t forget to change the JavaScript and User Agent settings in Safari back to what they were.
12. You may have to delete your Google account from your PlayBook and re-add it.

Note: You may have to set your Google account to US English before this will work.

Hope this helped,

Anthony - Wonder Reader for Windows Phone