I'd like to report a conflict between the Simple Google/Facebook Connect plugins and the Forms module provided by Jetpack.
When either of the two Simple Connect plugins (did not test STC) is activated alongside Jetpack, the Jetpack forms are simply not rendered on page. Creating the forms and inserting the shortcode all works like normal, the result is just not visible on the front-end.
I've also noticed that Simple Google Connect disables the (final) checkout button in eShop. I'm mentioning it here since it might be a related issue...