Toast is an example application meant to demonstrate a wide range of EclipseRT technologies. It operates in the telematics and fleet management domain. Telematics is the integration of telecommunications and informatics. You will have seen this in car navigation and infotainment devices. A typical telematics system interfaces to the devices in the vehicle and provides a user interface for interacting with or managing the devices. More sophisticated systems connect to a fleet management control center over a wireless network and allow remote control of the devices. For the fleet control center think of a large courier company with vehicles and packages going from place to place. This application domain is extremely rich with technology possibilities. That's why it makes such a great example!
Setup instructions can be found in the Eclipse Wiki.