Upgraded to WordPress 2.9.1 at HostMonster
I saw today that when I upgraded to WordPress 2.9 a while back, it broke the TimeZone plugin, and all the posts I'd made were 6 hours off. I also found that there was a new version of WordPress out - 2.9.1, so I went to HostMonster and upgraded my installs to 2.9.1.
I then went to the General settings tab and set the TimeZone there to be 'Chicago'. At this point, the TomeZone plugin correctly reported the time offset, and I should be OK. But I'll have to check and see what happens the next time we come to a time change.