I just checked in code for User Nickname which I think is a very important protocol extension and a missing part of XMPP. Never really understood the name attribute of the roster item since that is not set by that user.
As a client developer, while implementing a XEP, I often encounter problems with missing or incomplete server support. I guess this is inevitable in a client-server environment with distributed development.
While polishing The Coccinella I noted one extra dialog when another user removed me from its roster by sending a 'remove'. This extra dialog was identical to the one when another user rejects a subscription from me. A bit of tracking pointed to a presence with type 'unsubscribed' which is sent by the server in both cases. So I went to the protocol definition, RFC 3921 where it says in section 2.2.1: "unsubscribed -- The subscription request has been denied or a previously-granted subscription has been cancelled."