Anyone know if this is or ever was the basis for Apple's iCloud web apps on iCloud.com (e.g. Keynote / Pages / Notes etc.)? Those apps are heroic attempts to replicate the desktop app experience in the browser. I'm curious what web framework is underlying it. Side note - if I could install 3rd party apps w/ similar UIs in my iCloud dashboard that would be interesting.

I think originally Apple was using SproutCore, which had similar aspirations to produce "desktop quality" web apps, and was one of the early frameworks to implement things like two-way data binding. This was back when iCloud was called MobileMe.

SproutCore 2.0 became Ember.js 1.0, but I don't know if Apple are still using it.

Cappuccino was not an Apple project, so I doubt that is what Apple used to develop those projects. That, and 280 North eventually got acquired by Motorola.