Most of ESRI ArcToolbox tasks can be done using PostGIS functions. A first attempt to use thes functionality is the geoprocessing extension of QGIS (only Buffer support at this moment).
A new web interface would provide GIS geoprocessing operations in the same fashion of ArcToolBox.
This would extend the PostGIS usage for most GIS users looking for geoprocessing features. Later development would extend this concept to other OSGEO projects like QGIS(extend geoprocessing extension).
These details are provided for information only. No information here is legal advice and should not be used as such.