unless I got it all wrong, JBoss Portalsaves a user's timezone information as an offset to some other (GMT?) timezone. Isn't this error prone? Different timezones have different DSTs ...
I haven't looked at the dates stored by the portal, but I imagine that they are in GMT. Only when the date is displayed does the time zone and DST come into play. And all of that is handled by the JVM. So as long as the JVM handles DST properly, there should not be a problem.
See The Sun JVM FAQ on timezones http://java.sun.com/developer/technicalArticles/Intl/USDST_Faq.html