For the unaware, Embedded JBoss allows a developer to embed much of the functionality of the JBoss application server (EJB, Messaging, JNDI, Security, Transactions) in another application. A great use for the technology is in the creation of unit tests that can actually test Session, Entity, and Message Driven Beans. At Health Market Science, we heavily used the Embedded EJB container (a predecessor to Embedded JBoss) connecting to a in-memory Hypersonic DB for improving out unit tests. It made developing and debugging significantly easier and all of the developers loved doing it. I highly encourage any developer that is developing using EJB3, and especially anyone using JBoss, to use the combination of Embedded JBoss.
Full Presentation can be found at http://www.innovationontherun.com/presentation-files/Intro%20to%20Embedded%20JBoss.pdf