Remember when daylight saving time ended, how people complained about their iPhones and iPod touches' alarm failed to keep up with it?
That time, it was okay for me cause I live in Japan. But this time, looks like it's gonna affect almost all iOS 4 users. So be careful not to set your alarms on your iOS devices, or you might find yourself late for school, work or whatever. The bugs seems to fix itself by January 3rd.
Found the facts from http://onlinenewswebsite.com/apple-iphone-alarm-bug-silences-the-new-year/105389/ , so I'll give credit to them.