web2py 1.8

web2py comes in source code version (for any Operating System that runs Python) and in binary versions for OSX and Windows.

web2py does not need to be installed. You unzip it, click on it, and choose a one-time administrator password. It then opens the browser for you and directs you to the administrative interface.
Everything it needs to make this happen (the Python interpreter, the web-server, the relational database, etc.) is already packaged with web2py. If you need more power you customize your applications to use your preferred web-server (for example Apache) and your preferred database engine (for example PostgreSQL or Oracle).