PyWPS was recommended as WPS tool in the GIGAS project.
PyWPS Web Processing Service: is a Python program which implements the OGC WPS 1.0.0 standard (with a few omissions). PyWPS was chosen as it is up to date with the WPS standard and has a low footprint, making it easy to install on most Linux systems. Python was considered a good choice of implementation language as it is a very easy language to develop in and allows partners to easily integrate existing processing which may have been written in other languages. PyWPS documentation may be found at http://pywps.wald.intevation.org/documentation/index.html
See http://www.thegigasforum.eu/cgi-bin/download.pl?f=342.pdf for more.