[update 4/6/16]
PingIdentity added this functionality in 8.1:
- PingFederate publishes metadata: https://documentation.pingidentity.com/pingfederate/pf81/index.shtml#pf_c_connectionfederationmetadata.html
- PingFederate retrieves metadata: https://documentation.pingidentity.com/pingfederate/pf81/index.shtml#adminGuide/pf_t_manageMetadataUrls.html
Previous answer: PingFed doesn't currently have this functionality built in beyond turning on Auto-Connect. It is a current feature request.