In the astronomical Virtual Observatory, provenance metadata provide information on the processing history of the data. This is important to assert quality and truthfulness of the data, and potentially be able to replay some of the processing steps. The ProvTAP specification is an IVOA Working draft defining how to serve provenance metadata via TAP, the Table Acces Protocol, which allows to query table and catalog services via the Astronomical Data Query Language (ADQL). ProvTAP services should allow finding out all activities, entities, or agents that fulfill certain conditions. Several implementations and developments are presented. The CDS ProvTAP service describes provenance metadata for the generation of HiPS image datasets. The CTA ProvTAP service will provide access to metadata describing the processing of CTA event lists. ARI-GAVO prototyped specialized query functions that could facilitate accomplishing the goals of ProvTAP users.