GoogleTalk is a very odd hybrid system, which outwardly exposes an XMPP interface to clients as well as other servers. However, it does odd and possibly dangerous things, such as respond to Jabber messages via SMTP assuming that the JID is also a valid RFC 822 e-mail address.
In some systems, different users could own a Jabber account and an e-mail address which are identical except for the schema.
How did he do such terrific stunts with such little feet?!