The focus of Embedded JBoss is to be able to run the JBoss 5 Kernel and JEMS services with a non-JBoss-controlled classloader. What does this mean? It means you are able to run JBoss within the same JVM as a plain Java program, a junit test, standalone Tomcat, or even another application server. Why is this important?
Allows JBoss and JEMS products to be more "lightweight"
Allows people to use JBoss/JEMS that can't switch containers that easily
Unifies what other projects at JBoss are already doing to be able to run in non-JBoss-app-server environments.