Looks good. But I don't really care if I can style the editor with CSS3.
Concretely, why should I scrap my current code editor and start using Kod? Is it somehow targeted to Node.js devs; how is that better than Cloud9?
No browser stuff and Node.js is running in an isolated process. CSS is simply the "language" in which you define the looks of the editor and has nothing to do with web browsers or html.
Are you the author of Kod (that's what some of your comments suggest)? If yes, do you have a roadmap? Do you want to make it open source? I would be pretty excited to try it, out even if it was in scary-alpha state.
"Written from scratch with modern OS X 10.6 APIs providing maximum OS integration while avoiding reinvention of the wheel."
Though CSS styling and Node scripting leads me to believe it's using some v8/browser stuff.