Automatic Google Calendar sync

I am currently testing out the Appointments+ plugin in the hope of using it on a clients website. I wondered if it is possible to get the appointments (and time off) to sync through to a Google calendar?

One way sync would be useable, but two way sync would be amazing. My client requires that the appointments can be easily viewed on his iPhone, but I think having to manually click the Google calendar link for every appointment will be time consuming and tiresome.

Any thoughts on how to achieve this?