I've been wondering when someone would come out with a cloud-based IDE, although this isn't quite the same. I've always thought, wouldn't it be cool if Google came out with an online IDE, hosted on a GAE instance, with code saved in Google Code, allows you to build your code on their servers, and deploy to a dev GAE instance with seamless push to a production instance. For kicks (and probably an extra fee) you could have Google engineers do a code-review.
This is based on a web2py which has a full web based IDE although the web2py web based IDE does not run on GAE because of GAE file system limitation. cube2py has a partial workaround by storing everything in the database. Still before you run it GAE you have to run the code locally to create the indexes.
If your looking for a pure cloud based IDE you should check out http://kodingen.com/ I have played with it a little but and it seems pretty cool. I haven't done anything in production on it, but it is a lot of fun to play around with.
If the intention is to get non-technical folks to use it, I'd suggest a WYSIWYG editor would help enormously.
Knowing that a blank line is required before space-asterisk-space to make a bullet in a markup language is more than most people know or can be bothered to learn.