Sphinx is a free, open-source Python document generator. Visit the stable and development(http://sphinx-doc.org/latest/) version webpages for more information.
pip install sphinx and
pip3 install sphinx only installs the latest stable release, which is 1.1.3 as I write this.
pip will not install beta or development versions.
Install the latest Python versions on Mac OS X Mountain Lion (10.8) has instructions on how to get pip and pip3 on your Mac using Homebrew.
To install a specific version of Sphinx, say the 1.2b1 beta/development version:
pip install sphinx==1.2b1
To install the latest version of Sphinx, including beta/development versions:
pip install sphinx --pre
To see more installation options for pip:
pip help install