I'm happy to announce the first public release of XDo (it's part of the Automations project). XDo is a library that lets you fake and automate (simulate) user actions on a Linux X Server system like Ubuntu. You can send keystrokes, move the mouse, manipulate windows, ...
It's based on several command-line tools for X, notably xdotool which should be installed before:
http://www.semicomplete.com/projects/xdotool/
Or just
sudo apt-get install xdotool
if you're running on Ubuntu. Then install XDo itself via RubyGems:
sudo gem install xdo