Hi Joe,
I have replicated this on the demo website.
If you set the Event Calendar Time Zone to Central Time (GMT-6) and then create an event at 6pm that and have it repeat weekly for 1 year, all subsequent events will show up on the following day. For instance, I created an event named "Weekly Wednesday Event" starting on 1/12/11 at 6pm - 8pm. I set the event to repeat weekly until 1/11/12. After saving, the event showed up on Wednesday, 1/12/11 AND Thursday 1/13/11 and repeated on Thursday until 1/12/12. If I changed the time of the event to 5pm or before, the problem didn't occur.
Testing this further, I set the time zone to Mountain Time (GMT-7) and the same problem occurred.
Let me know if I can provide any further information.
Thanks,
Joe