I have created these two screen-casts explaining this feature.
Please watch/listen to them at:
You will need QuickTime Player installed. Here is the transcript:
Hi, my name is Kedar and I am administration/management architect for GlassFish V2. Welcome to this GlassFish V2 Screen-cast.
Owing to growing popularity of clustering features of GlassFish V2, from build b48...