I don't think it is a blackberry problem.
In fact, based on what you posted, it is working as expected. The phone utilizes local time zones. Unless there is a way to lock the phone to another time zone (which more than likely wouldn't work, for phone service) ... then I do not see a way of preventing this behavior.
But, I think this explains why I have a user with an appointment showing this:
GMT-6: 7 PM on Sunday (In Outlook/Exchange)
GMT-6: 4:30 PM on Monday (On the Blackberry)
I posted my thoughts on this topic (based majorly from the information on the first post here) Inexplicable Time Difference Between Task on Blackberry and Outlook - RIM BlackBerry - Wireless Forums from AT&T
As you will note, according to RIM, the tasks aren't supposed to synch?! "This is by design." What a joke.
Just tell me which time zone is 21.5 hours ahead of U.S. central standard time (heck, even 20.5 hours would work, as I could blame an extra hour on DST ... hehe)