Nuxeo EP comes as several packaged applications (Core Server, CAP, DM, DAM, etc.) that are usually bundled with a web container.
As of November 2010, our preferred web container, for production as well as for development, is Tomcat.
If you need to use a full-stack application server supported by a third-party vendor, we also provide packages bundling JBoss (4.2 for some of the older packages, 5.1 for more recent ones).
You can also download the Nuxeo DM application as an EAR (Enterprise Application Archive) and put it in your existing JBoss server, as long as you're using the version that we are supporting. Contact us if you need more details.
You can find a more detailed discussion here: Which Nuxeo distribution should I choose - JBoss or Tomcat?
We also provide a package bundling Jetty, that geared towards developers, and should not be considered production-ready.