My version of Glassfish is quite out of date (v3-b47). Since the java:app and java:module namespaces don't work for me either, I'm going to take a guess and say it may not have been implemented when Glassfish v3 Preview (that was b47, right?) was released.
I'll update to v3 final and give it another try in a couple weeks (I leave for a two week vacation tomorrow - yay!).
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