The switch from Daylight Saving Time to Standard Time happens tonight at 2 am. But as we learned from Australian and and European iPhone users, the iPhone's alarm clock will not recognize this change. In fact, your alarm is likely to go off an hour late.
This is a very strange bug. Australian users were reporting that their alarms were going off early after the time change, and European iPhones were going of late. Even stranger is that we received reports of people in the US already being affected by the bug - their alarms are going off early.
The key thing to note about this bug is that it does not affect one-time alarms. So if you have a recurring alarm that wakes you up for work each morning, change the repeat interval to "never". It's very frustrating to need to set the alarm every day, but it's the only option until Apple releases a software fix.
The good news is, it is fixed in iOS 4.2 which might be coming as early as next week. The bad news is that's a week too late to help with this bug. I don't know about you, but I'm really disappointed in Apple for not releasing a quick fix for this bug. They knew about it, so they should've fixed it before the time change.