I 'd like to share the slides from the keynote that I gave today at XV Pernambuco Python User Group Meeting about Scientific Computing with Python. This keynote presents how you can start in the scientific world using several tools in Python such as Matplotlib, Scipy and Numpy.
You can see it here.
It gives an overview about how you can start and basic introduction for those tools. It is in portuguese, since it was for a brazilian audience.
Any doubts, let me know.