IPython is great.
It's a full Python, with many of the most useful and popular extensions for numerical computing and visualisation.
For many, it is the place to do both Python programming, numerical computing and data science.
Even better, IPython can be pure web. That is, you can work with it, fully and interactively, using only a modern web browser. No need to install and configure any software at all. This is immensely powerful, because you can keep your work in the cloud, leave and carry on at a later time from any device with a browser, be that a laptop or a tablet, or even a smartphone.
Now imagine Google with its vast compute and storage resources offered an IPython service. That would be an immensely powerful combination.
Plus they'd love the social sharing of IPython notebooks.
When, not if?