[jdh]

Are they appearing in the iOS Calendars app? If they're showing up there, then they should also appear in OmniFocus, as that's where it gets them from.

If you're using a third-party app like CalenGoo that connects directly to Google Calendar, then this would be your problem, as the calendars aren't available to iOS and therefore aren't available to OmniFocus either. You basically need to configure your Google account under Mail, Contacts and Calendars in your Settings app in order for OmniFocus to see them. The instructions in my post above explains the two different ways to do this.