web.py 0.39 is the latest released version of web.py. You can install it by running:
pip install web.py
The above version only supports Python 2. If you looking for Python 3 support, try the experimental version.
pip install web.py==0.40-dev1
Or to get the latest development version from git:
git clone git://github.com/webpy/webpy.git ln -s `pwd`/webpy/web .