On request of customer I am working on integrating Project Hours with Google Calendar. Work has been progressing nicely and a fully functional demo is available on the project hours test site: Google Calendar in Project Hours. What it does is that every time hours are saved in Project Hours via the web interface or mobile app, an entry is created in a specified Google Calender. Only one (company) calendar per organisation can be specified.
In this way, a dashboard with work items is created that can be used for planning for example.
I am thinking of adding a feature where users can specify their own Google calendar for a per user overview. Or an integration the other way around: use Google Calendar to register hour entries in Project Hours. I have investigated this and it looks like the only way to do this is to create a Chrome plug-in that adds Project Hours menu items to the Google Calendar web page. But first we are going to do some testing and release this to the Project Hours production environment. To be continued..