[JDEV] How to get user name from a JID?

[Jens Alfke]

How does one look up the real name associated with a Jabber ID? I've 
taken another look through the docs but don't see anything obvious, 
other than retrieving the user's vCard (if they have one). Since the 
server asks for your first and last name when you register, it must have 
this info already, but I don't see a way to get it...

(The main reason I want this is so that when a presence subscribe 
request arrives, I can show the full name of the user making the 
request.)

--Jens