pycsw is an OGC CSW server implementation written in Python, enabling publishing and discovery of geospatial metadata, providing a standards-based metadata and catalogue component of spatial data infrastructures. This presentation will look at the history and motivation of pycsw, current developments, and why pycsw is quickly gaining momentum as the choice for CSW deployments among many open data portals (GeoNode, Open-Data-Catalog, CKAN/data.gov). The project is certified OGC Compliant, and is an OGC Reference Implementation. Since April, pycsw is under OSGeo Incubation.