James Snell has a piece at IBM developerWorks on how to Advertise Web services with Atom 1.0. He provides a code example:
The example presented here was designed as a simple illustration of how Atom 1.0 can be combined with WS-Addressing to solve, in a simple way, the problem of discovering when new Web services are available without requiring the invention of yet-another-XML-format.
This doesn't help with questions like how you found the feed in the first place, and how you tell what the service actually does (beyond what's in the WSDL). But it does seem to cover a useful part of the puzzle rather neatly.[Danny]