I just dont think XMPP fulfills the uncontrolled and uncensored and surveillence resistent parts. We need to look at web of trust, bitmessage and such instead, those are more fun problems than "to spite facebook".

But sure, any solution will benefit greatly if its bundled with the browser since that appears to be the only program most users actually use on their computing devices. Imagine if Tor and a tor-relay or even tor-exit-node came preconfigured with every Firefox and turned on by default. That would be fun.