There are several customised versions of the PayPal payment classes floating around. So, does anyone have a version with Instant Payment Notification (IPN) implemented? If so, it would be useful if this code could be merged with the official version. You can post your code or patch to the [url=http://code.google.com/p/silverstripe-ecommerce/issues/detail?id=201]enhancement request[/url]. In fact, it might be worth collecting up the various versions, and pulling the best bits of all of them together.