The idea behind GSW is to have “discovery, query, and consumption of geospatial content … based on formal semantic specification.” An OGC Interoperability Experiment which “aims to augment WFS/FE with a semantic query capability, through the definition of an ontology for the geospatial intelligence community.”
The GSW will enable the meaning of geographic queries to be easily shared among different software systems and online services.
Source: http://www.opengeospatial.org/projects/initiatives/gswie