CoMotion is at the University of Washington, they have a Kobuki Turtlebot 2 base, the Elcano project will show off their robot (which isn’t a ROS robot, but is interesting regardless), and I’ll go over a xacro/urdf example 4-wheel mobile robot being driven in rviz and Gazebo.
http://www.meetup.com/RobotOperatingSystemSeattle/events/231816956/