I have an OpenID relying party setup and using XRDS. It passes the "RP has discoverable return_to" interop test over at http://test-id.org/RP/DiscoverableReturnTo.aspx.
Yahoo no longer complains with the message "Warning: This website has not confirmed its identity with Yahoo! and might be fraudulent." as outlined in Andrew Arnott's excellent blog post: http://blog.nerdbank.net/2008/06/why-yahoo-says-your-openid-site.html
However, when I try to authenticate using AOL I see the "Warning! site verification could not be completed." message.