This is a cool implementation, but the idea is not new. In fact, the majority of front-end JavaScript libraries right now are more or less aiming to do the same thing in their own way: AngularJS, Meteor, Ember, KnockoutJS, Bacon ... even d3js. The list goes on. These are all attempts at implementing reactive programming in the web, but they have different data and data binding models, and they may have different front-end goals (e.g., Ember tries to keep a 1-1 correspondence between document state and URLs).
There's also Elm, which implements a variant of reactive programming known as FRP.
I don't think AngularJS, Meteor or Ember are close to this though. The result might be the same, depending on the use case, but the philosophy isn't.
AngularJS for instance looks like more about components and data-binding (makes me remember the old Delphi days) in an attempt to use the browser as an application framework than "interactive documents".
Those libraries are ultimately just more sophisticated versions of this on a bigger scale. Meteor in particular takes reactivity to a whole new level: changes are propagated immediately not only to you but to other users as well (if appropriate to the application, e.g., a chat room). The philosophy is more or less the same in all cases: make the page react immediately to what the user is doing without a full refresh. Some of those libraries take it further and tie the page directly to the application back-end or database if desired.
I think the main appeal of something like Tangle is to get the benefits of reactive programming while using only a very lightweight and simple library. It provides a very clean interface to a subset of the functionality.
There's also Elm, which implements a variant of reactive programming known as FRP.