If you have not yet groked why there are multiple open source communities developing application servers - the answer is that choice is good for developers and keeps suppliers innovating. Here is a great thread on Java.net discussing the GlassFish and JBoss communities and thier relative merits. The one missing piece of information in this is that the application server developed by the GlassFish community is used by Sun, to create our documented and supported application server (SJSAS PE 9) which will be a robust, commercial product when the Java EE 5 spec is finalized and the app server is finally released by early Summer of this year.