https://docs.google.com/spreadsheet/viewform?formkey=dDdGcHE...
What's unique about what you have here is the realtime collaborative editing. We use NestaCMS (which also understands Markdown) hooked up to a Dropbox folder in a few places. The functionality is similar, but there's no in-page editor, and we can't collaborate in real time.
Both of those things have value to me, but I have serious reservations about jumping on to a wiki product that I can't control. Documentation is a complete pain in the ass. When I put time in to it, I need to feel 100% confident that I won't have to abandon it at a future date; either because I run up against a feature ceiling, or because you disappear. And if I do have to leave, I need to be able to get my information out of the system.
You should really add a minimal homepage with an email signup as well if you intend to work on this more. The product is self explanatory so I don't need marketing text but I'd love to be able to be notified if you come out with accounts, open-source it, add a paid plan or allow installs to my server.
All in all, great work and congrats on shipping something!