I created a new "xwidget" branch. It is a very experimental branch that
allows gtk widgets to be embedded in an emacs buffer, much like images.
It is, for instance, possible to embedd a browser in an Emacs window.
See some screenshots here:
http://www.emacswiki.org/emacs/EmacsXembed
Soem screenshots of Daivd Hackneys work to embed the usbl browser:
http://www.haxney.org/2009/08/its-alive.html
There is also a README in the root of the branch.
Please note that the code really is experimental and that there are a
number of hard problems still unsolved. That said, I still find it very
cool to see gtk buttons moving in an Emacs window, and even Emacs
embedded in Emacs :)