When I first starting working on a BlazeDS application, it wasn't too difficult to build the example flex application using FlexBuilder, then deploy on JBoss. However, once I started attempting to build using Ant, I started to run into some problems. Using a seemingly correct build script resulted in a non-functioning flex build (it is pretty easy to tell, since you can see in the lower status bar of your browser that there isn't any communication with the server).

Directly compile actionscript from your java application - makes sense since I believe the flex compiler is encapsulated in a jar.

Overview of what's due in Java 7.