Built out of WebKit and Node.js.
Runs as a desktop app on Mac, Windows and Linux, and can be hacked into any WebKit browser (Chrome, Safari).
Follow TermKit on Twitter for the latest news and updates.
For the background and architecture, please read and comment on: http://acko.net/blog/on-termkit
(but you could make it do most of those things with plug-ins)
Detailed instructions are available from these sources:
Unfortunately, TermKit currently requires some assembly.
curl http://npmjs.org/install.sh | sh
npm install mime
git clone https://github.com/unconed/TermKit.git --recursive
git submodule update --init
cd TermKit/Node; node nodekit.js
Tip: Press C to access the WebKit console.
Preliminary instructions on how to write TermKit native commands can be found here: https://github.com/unconed/TermKit/blob/master/Node-API.md
Windows port by James Rhodes (@hachque).
Linux Python/GTK wrapper by Lucas S. Magalhes.