Thanks all who responded. I think I've solved the problem, but I'm not sure yet, so I'll leave this question still showing that my question has not been answered yet. I'll explain.
I've been doing development on Windows and my server is Linux. I now have the JDBCRealm working on Windows. Unfortunately, I can't test on Linux until this weekend, as the server is currently in use and I don't want to disrupt it -- possibly for a long while if something goes wrong.
Anyway, here's what I've found thus far.
Glassfish v2b41c (and probably other builds around this timeframe) have a bug in which if you create the JDBCRealm using the admin console, the <group-table> element is not saved. So, I think what has been happening is that I ran the JDBCRealm with no group-table. This would explain why it didn't work -- what it doesn't explain is why I was seeing FileRealm being consulted for the login authentication in the GF server.log. So, I will do more testing over the weekend, and will report back here -- and will post a bug report on the admin console problem.
Rick
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