We announced a new communications product, Hangouts, in May 2013. Hangouts will replace Google Talk and does not support XMPP.
Google Talk is Google's implementation of the open standard XMPP, or the Extensible Messaging and Presence Protocol. For more information about XMPP, please see its official website and its wiki page.Because Google Talk supports open standards, it is fully interoperable with other communications services that support the open server-to-server XMPP protocol. This means that users of any of these services can communicate directly with Google Talk users, and vice versa. Here is a list of just some of the service providers that already support this open industry standard.