By default, only the default calendar syncs to the iPhone and iCal. In order to enable sync for other calendars, go here: https://www.google.com/calendar/iphoneselect

Another source says you need to go to http://m.google.com/sync on the iPhone and enable the calendars there. But this doesn’t seem to work for me.

Source: http://www.google.ru/support/forum/p/Google+Mobile/thread?tid=7185584b4240c70…