I’m excited to get this plugin working but I think I have kind of the same problem.
I’m running WordPress 3.3.2 and Crossposting 1.1.1. I can enter and save my Google+ ID but when I enter my activated Google+ API and save I get a Server error (!?).
“The website encountered an error while retrieving https://192.168.1.100/wp-admin/options.php. It may be down for maintenance or configured incorrectly.”
And the API key is gone. As you can see my webpage is not public yet but I’ve managed to get other plugins working so I don’t think that has anything to do with it.
Hope to get this up and running soon ??