XeTeX is Unicode-based TeX using platform fonts and font technologies (e.g. AAT on Mac OS X or OpenType features on Mac/Linux/Windows) to provide typesetting for all the world's scripts.
A bundle of lisp extensions, largely original, for GNU Emacs with the goal to obtain a more user friendly and powerful interface. The new features include contextual tool bars, new TeX interface, very complete menus, and a well structured IDE.