From a cursory reading, this isn't particularly new, even on the web. Essentially what he's done is implement bindings/key value observing, but with a new syntax instead of the one we already know (i.e., javascript). On the desktop Cocoa has done this very well, and on the web Cappuccino and SproutCore have copied the cocoa approach. There are also more lightweight libraries that provide binding support without a heavy framework.