<p>I've been doing "plain old java objects" programming for 10 years now, with Swing and JDBC, and I consider myself pretty good at it.  But I start a new job in two weeks where they use JBoss, and I'd like to get a heads up and start learning all this stuff before I start.  What are good resources?  On-line tutorials, books, e-books, anything you can suggest, especially ones that don't try to teach you the basics of plain Java first.</p>

A couple of answers come to mind:
if "plain old java" is what you're used to, you'll probably need a grounding of plain old j2EE more than JBOSS specific stuff. I'd start with
the sun tutorials
, but being familiar with the general structure of servlets, the servlet api, is base.
as application servers go, JBoss is (my biased opinion only) insanely large and complicated. Think "launching the space shuttle" and you won't be far off. A million services. It is specifically noted for having an unusual class loader structure (although this may have changed since I used it last, about 1 -2 years ago), among other things. It also has an extensive list of nice services, like a JMX base (management configuration beans) although documentation is likely to be spotty, as support is a paid service.
Best suggestion- familiarize yourself with the J2EE libraries. Next would be to get a basic site running in JBOSS. More specific stuff that you might want to do is likely to be very specific to their installation (e.g. there's a JMS implementation available in there but they may not be using it) as I've seen people use it for nothing but a servlet container.