Gravity Forms by default will write an inline JavaScript call to jQuery on every form you add to a page.  This will throw an error if you’re loading jQuery in the footer of your site (which you should be doing).  This is the error:

Uncaught ReferenceError: jQuery is not defined

There’s an extremely hidden bit of documentation on how to override this behavior here:

<?php
add_filter("gform_init_scripts_footer", "init_scripts");
function init_scripts() {
return true;
}
?>

This code should be placed within your theme’s functions.php file.

http://www.gravityhelp.com/documentation/page/Gform_init_scripts_footer