I had some small issues that I want to share.
1) After you have a calendar on google, have your setting to public and sharing.
2) open the calendar and click the XML little icon to get the FEED info
3) go to the wordpress settings and enter the FEED - do this for each calendar you have on google.
4) set the parameters on the page or post to display the calendar info or grid.
Where I was stuck was that the google FEED name is not HTTP:// but HTTPS
Keep you eyes on the exact wording used to get the feed.
Otherwise - works with 3.5.1
I will test widgets but I have what I need on a page or two.
I think the link works fine on the eventlist code but the GRID shows the date of the event but it is not allowing for the click to the event details? Can the GRID function allow for a user to click and send them to the event details?
Let me know if I need to do something else.