Here's my project to demonstrate the modern software process: peppy. It'll eventually be an XEmacs workalike in wxPython.
peppy has had a major overhaul and is actually sort-of usable for editing. It's got major modes, minor modes, global plugins, dynamic menu/toolbars, the AUI widgets to manage the layout, and Trac components for plugin extensibility. (And other stuff.) Still very alpha software, though, but I'd be interested in any feedback.
I'm looking forward to having a tool like this! --RobinDunn (yet another multi-decade Emacs user)