It seems to be heavily broken right now, or heavily unstable. Hmpf... I'm trying to start the ipython notebook (you have to do this on demand), then you can start editing the files ... but it is stuck. Now it's completely broken.
The terminal works fine now, and a project is running in some kind of isolated container in beefy linux ubuntu 14.04, running under a common "sense" user (which is the only user). They are also running some node.js client and their "butterfly" server.
Ok, well, I tried to test it further or add a collaborator, but the website just says "502 application not responding".
It didn't seem like they have real-time editing or LaTeX.
few more details. ... now it runs fine again. two screenshots attached. ... one is the project view, the other one the "workbench".
They run a plain "R" terminal, but with a neat HTML output. It's a vertically split editor, where the .r file is on the left, and you can select lines of text which are then executed via "ctrl+return". That's exactly how those R people work (instead of having cells like ipython or sagews)
The same for python files: one or all lines are fed into the "ipython terminal", not the notebook (!), and then translated to some html output on the right. plots work fine, etc.
So, on the right of the screenshots, you can see the copies of the input lines.
By default, they add a .gitconfig file with the username and email address. That's cool, and I guess this could be done for SMC as well.
There is no auto-save for files, just lost the content.
-- William Stein and Harald Schilly