Hangouts Plugin for libpurple is a replacement purple for hangouts in
Pidgin/libpurple to support the proprietary protocol that Google
uses for its Hangouts service. So far it supports all the fun things
that aren't part of the XMPP interface, such as Group Chats,
synchronised history between devices and SMS support via Google
Voice.

WWW: https://bitbucket.org/EionRobb/purple-hangouts