Thoughts on .tel and WebFinger

This is a really interesting discussion, spurred by Dave Winer's posts on the need for a global namespace for dispersing microblogging away from centralised services:

http://www.scripting.com/stories/2009/08/06/anotherBrickInTh...

http://www.scripting.com/stories/2009/08/07/tradingOneCentra...

http://www.scripting.com/stories/2009/08/13/looselyCoupled14...

What's the best way to resolve simple usernames to feeds (and other endpoints)? .tel? webfinger? i-names? Something else? All of the above?