Twitterbot is a project mainly written in Ruby, it's free.
Twitter Jabber Bot
DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
Version 2, December 2004 Copyright (C) 2004 Sam Hocevar [email protected]
Everyone is permitted to copy and distribute verbatim or modified copies of this license document, and changing it is allowed as long as the name is changed.
DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION