No invite yet, but from what I see from their blog (http://blog.koding.com) Koding seems to offer all kinds of collaboration-coding tools via your web browser (for free). Version control springs to mind, as does my code trusted to the "cloud".
"Cwis Packham's made me a tiny little saddle (with little reins and stirrups and everything). Told him I'm not wearing it. Now he's in tears. A peacock just asked me to be the best man at his wedding" ~ @GusTheFox