"There are only two hard things in Computer Science: cache invalidation and naming things." -- Phil Karlton

There is not an easy solution to the "problem" that this article describes.

The current situation allows us to look up numbers without letting some central authority know what numbers we are looking up and without letting them have our address book. Any solution to this "problem" is likely to reduce everyone's privacy by getting rid of one of these features.

EDIT: You can contact me using the same "username@domain" style address for email, XMPP and SIP. I guess that's something. People still need to store my "username@domain" address in an address book though.