This is the servlet container included with the uPortal quickstart. This is probably the most common of the containers listed here.
The build.xml has support for deploying to your Tomcat installation. All you need to do is set the server.home property in build.properties to point to your tomcat installation. Then you can run "ant deploy" to deploy to tomcat. You will need to restart tomcat at least the first time. Reloading the context after that will work.
Please edit this page to add more insight about making uPortal run in Tomcat.