Connecting to GTalk (jabber.org works) yields the error "Invalid authzid":
16:52:01: (Libpurple: jabber) Sending: <?xml version='1.0' ?>
16:52:01: (Libpurple: jabber) Sending: <stream:stream to='gmail.com' xmlns='jabber:client' xmlns:stream='http://etherx.jabber.org/streams' version='1.0'>
16:52:01: (Libpurple: jabber) Recv (386): <?xml version="1.0" encoding="UTF-8"?><stream:stream from="gmail.com" id="16CE5C3E3D33B8C9" version="1.0" xmlns:stream="http://etherx.jabber.org/streams" xmlns="jabber:client"><stream:features><starttls xmlns="urn:ietf:params:xml:ns:xmpp-tls"><required/></starttls><mechanisms xmlns="urn:ietf:params:xml:ns:xmpp-sasl"><mechanism>X-GOOGLE-TOKEN</mechanism></mechanisms></stream:features>
16:52:01: (Libpurple: jabber) Sending: <starttls xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>
16:52:01: (Libpurple: jabber) Recv (50): <proceed xmlns="urn:ietf:params:xml:ns:xmpp-tls"/>
16:52:01: (Libpurple: jabber) Sending (ssl): <stream:stream to='gmail.com' xmlns='jabber:client' xmlns:stream='http://etherx.jabber.org/streams' version='1.0'>
16:52:01: (Libpurple: jabber) Recv (ssl)(176): <?xml version="1.0" encoding="UTF-8"?><stream:stream from="gmail.com" id="6449CEB16DAD8A1F" version="1.0" xmlns:stream="http://etherx.jabber.org/streams" xmlns="jabber:client">
16:52:01: (Libpurple: jabber) Recv (ssl)(166): <stream:features><mechanisms xmlns="urn:ietf:params:xml:ns:xmpp-sasl"><mechanism>PLAIN</mechanism><mechanism>X-GOOGLE-TOKEN</mechanism></mechanisms></stream:features>
16:52:01: (Libpurple: jabber) Sending (ssl): <auth xmlns='urn:ietf:params:xml:ns:xmpp-sasl' mechanism='PLAIN'>(removed)</auth>
16:52:02: (Libpurple: jabber) Recv (ssl)(78): <failure xmlns="urn:ietf:params:xml:ns:xmpp-sasl"><invalid-authzid/></failure>
16:52:02: (Libpurple: jabber) Recv (ssl)(16): </stream:stream>