XMPP is actually managed by the IETF. The XSF just develops extensions to the protocol (but it's not the official steward of XMPP, confusing as the name is)
Indeed; that's why I think this model has worked pretty well. You get a nice core protocol and then if you want fancy features that keep up to date with proprietary offerings that can be developed in a lighter weight way. Certainly not perfect, but I'm glad the IETF is in charge of the core spec and not the newer, less experienced, foundation (though at this point the XSF is well established too, but in the beginning it was the close relationship with the IETF that let it build that institutional knowledge).
