Python Web Processing Service is an implementation of the Web processing Service standard from Open Geospatial Consortium.
It has been started in May 2006 as a project supported by DBU and is currently (2009) mainly sponsored by HS-RS. It offers an environment for programming own processes (geofunctions or models) which can be accessed from the public. The main advantage of PyWPS is, that it has been written with native support for GRASS GIS. Access to GRASS modules via web interface should be as easy as possible.
PyWPS is written in Python, your processes must use this language too.