Myself(S. Prasanna Venkadesh) and my brother (Sathia) has developed a Ruby script which can be run from linux terminal and you can connect with your Google account and start chatting with your contacts.
Check our public repository at GitHub: https://github.com/PrasannaVenkadesh/Whiz-Chat
You can download the source code from the above link and you can run the ruby file in your terminal.
Before running it make sure that you have Ruby Version 1.8.x and Rubygems1.8 and espeak installed in your linux system, if not please do install it.
If you have latest version of ruby (1.9) you can use version 1.8 by rvm use command(google for it).
Please post whatever bugs you find in it. Thanks for reading this.