I have Odoo 8 installed on a Windows 7 Ultimate 64 bit pc for my business.  When I originally configured the Google Calendar sync, all of my all day events were duplicated a day earlier.  When I sync a new all day event in Odoo, it is moved back one day in both calendars.  When I create one in Google, they both sync with the correct date.  When I create a time specific event in Odoo or Google, it syncs to the correct date.  I also tested using the online trial with the same results.

After researching on Odoo.com and google, I thought it might be a time zone issue, but the pc, Odoo and Google calendar are all set to the same time zone.  I changed the Odoo time zone from America/Los Angeles to US/Pacific and restarted Odoo.  I also tried changing the google account time zone back and forth serveral times.