IPython Notebook is the perfect complement to IPython. As per the IPython website:
"The IPython Notebook is a web-based interactive computational environment where you can combine code execution, text, mathematics, plots and rich media into a single document."
While this is a bit of a mouthful, it is actually a pretty accurate description. In practice, IPython Notebook allows you to intersperse your code with comments and images and anything else that might be useful. You can use IPython Notebooks for everything from presentations (a great replacement for PowerPoint) to an electronic laboratory notebook or a textbook.
If you have completed the installation instructions in the first chapter, you should be ready ...