The PyWPS development team has just released the first beta version of the upcoming PyWPS 4.0. This new release is a complete re-write of PyWPS, taking full advantage of modern Python technologies.
For a bit of history and a quick overview of PyWPS-4 there is this presentation.
For a more in depth information please consult the article recently published by ISPRS.
The source code for this beta release is available at GitHub. Please follow the documentation to install PyWPS 4.0 and the accompanying demo application.
This beta release aims to fully comply with the WPS 1.0 standard and support seamless integration with GRASS GIS. Please report your feedback at the PyWPS mailling list, or open an issue at GitHub.