The WebSphere Service Registry and Repository Handbook has now made it out of draft. Having submitted a whole raft of feedback on an early draft I did appear in the acknowledgements but mysteriously my name hasn’t made the final cut! Notwithstanding this, the book provides excellent coverage from the basic concepts, through installation, to advanced customization, governance and integration with WebSphere ESB, ITCAM for SOA, WebSphere Message Broker and CICS. (Note that, as of the recent 3.6.0.8 firmware version, DataPower can also be used to perform lookups in the registry.)
One topic that the WebSphere ESB chapter covers is how to connect the endpoint lookup mediation primitive to WebSphere Service Registry and Repository via SSL. This doesn’t currently work out of the box. You will need to apply APAR IC51354 to WebSphere ESB and then follow the instructions in the book or corresponding technote.