Although I frequently use Numpy I'm far from an expert and the content of my talk reflected this. I started with a general introduction to the array object and then expanded the scope of the talk to highlight some of the projects that use Numpy. I gave an example of using MDP and matplotlib.
The talk was followed by some excellent discussion. We went through some of the code on slide 6 in a lot of detail.
The PyNorthwest group meets at Madlab in Manchester city centre on the third Thursday of each month. If you're in the area check it out. The January event is on the 19th, starting at 7pm.