JBoss is going to be a cornerstone of our new infrastructure. We will be using a slightly newer version of the JBoss EAP stack with components from the JBoss SOA team to incorporate the JBoss ESB.
Make sure you are comfortable with starting and stopping JBoss as well as the server configurations, deployment mechanisms, jmx console, and general filesystem layout to find logs.
These documents aren't incredibly thorough at the moment, but it should give you a good initial understanding of the JBoss ESB technologies.
The reference documentation for Seam 2.0 CR3 will probably be the best document to read through.