Actually a lot of their ideas are similar emacs. Have a few core pieces written in C and then everything else is written in elisp. Even the stackable navigation and WebViews are the equiv of buffers.

Conkeror already has stackable navigation and can be extended using javascript. In many ways the ExoBrowser is simply taking Conkeror to it's logical conclusion.

Very interesting, I'll be interested in seeing where this goes in the future.