Update (Feb. 13, 2009): To sync multiple calendars, go to m.google.com/sync on your iPod touch/iPhone and select additional calendars to sync.
Last September, I posted How to: Sync Google Calendar with iPod touch/iPhone in which I explained how to use the free NuevaSync service to sync Google Calendars (and contacts) with your iDevice. That post has gone on to become the most searched/visited/read story of any post (besides my 2009 Inauguration coverage) on Boilr in the last 4 months.
As such, it seemed only fitting that I post an update in lieu of Google’s announcement earlier this morning. Now, instead of using a third party solution, you can simply use the official Google Sync app to sync your Google Calendars and Contacts with your iPod touch / iPhone (or any of the other supported mobile platforms). Cheers!