This was created from scratch by a small team at Manifest Digital.
I was responsible for back-end development, as well as Ajax development. jQuery UI is used for most user interactions with the site.
Authentication and field pre-population are handled with Facebook Connect and jQuery UI.
All of the site's functionality (including CRUD functionality in the gift list) is accessible from an associated iPhone/iOS application. I built an API for this purpose, whose transactions consist of signed HTTP Posts and JSON responses. Users with the iPhone app can view and modify public and personal data either on their device, or on the web.