Edit “thank you for creating with WordPress” in version 3.3.1

Credit definitely goes to @kaiser, but here is a full working solution. You can add this code to your functions.php file (in your theme):

function wpse_edit_footer() {
    add_filter( 'admin_footer_text', 'wpse_edit_text', 11 );
}

function wpse_edit_text($content) {
    return "New Footer Text";
}

add_action( 'admin_init', 'wpse_edit_footer' );