The plugin doesn't seem to be working for me. I think it's because the click handlers appear to be added on $(document).ready, but my checkout forms (1 for CC, 1 for Paypal) load async after the ready event fires... so the checkbox never registers the click events.
Steps to reproduce (staging site w/ only test payments):
1. Go to http://staging.mastinlabs.com/store/ and click "Add to Cart" then "Checkout" on any of the items
2. See that the "Purchase as gift" checkbox is not functional