Get a package from aptitude
sudo apt-get install ros-groovy-joystick-drivers
Follow this tutorial, start from topic "1.2 Configure the Joystick" onward, to configure a permission.
To start using the node, just run
rosrun joy joy_node
When node is running, you should be able to see topic named "/joy". To see data flow, just run
rostopic echo /joy
Tested using Xbox360 joystick for Window, on Ubuntu 12.04 running ROS Groovy.