In this 7-minute demo Tom covers the use of local or ssh commands to create remote node and instances grouped in a cluster.
Tom also demonstrates deployment with a single command of applications to that cluster showing how cluster provisioning and application deployment can be fully carried out from a central location using the command-line but also how the Web Admin console offers the same set of features in a graphical environment.
To read more about the clustering infrastructure in GlassFish 3.1, you should check out the High Availability Administration Guide documentation (of course!) but also read this new "Clustering in GlassFish Version 3.1" article on the GlassFish site.
This screencast is hosted on the GlassFish YouTube Channel.