On the other hand there is a much larger group (if only non-math students) for which a "google docs/github" for shared, zero-install, browser based python/R/Ruby programming, data-analysis, plotting, statistics, technical-scientific writing /Numpy numerical and yes, Sage symbolic computation environment is a great proposition. Of course this is exactly what SageMathcloud is offering. However, if I may exaggerate a bit, SageMathcloud is now positioned as a cloud system to support mathematicians that can also do things like plotting and statistics, because it is really handy for doing statistics of the zero's of the zeta function. Completely understandable from where you come from, but a marketing disaster. A name like Jupyther cloud that reflects such a "neutral" programming/technical/statistical/data position would be a great boon.