Tomcat and Jetty are very similar. Jetty can be invoked and installed as a stand alone application server. It has a flexible component based architecture that allows it to be easily deployed and integrated in a diverse range of instances. The project is supported by a growing community. The Jetty team has a history of being responsive to innovations and changing requirements.
They walk you through the "quick install" version of Jetty, getting it running, installing Quercus and configuring the Jetty web server to work with it.