There's also o'reilly's 'Introduction to Machine Learning with Python', which is very much about scikit-learn

http://shop.oreilly.com/product/0636920030515.do

Just came out a few weeks ago so it's relatively unknown, I've read the first few chapters and so far it's good! The first author Andreas Mueller is one of the scikit core devs.

The Jupyter notebooks including the book's code are on GitHub: https://github.com/amueller/introduction_to_ml_with_python

O'Reilly's publishing Introduction to Machine Learning with Python by Sarah Guido and Andreas Mueller in January 2016.

http://shop.oreilly.com/product/0636920030515.do