There is an alarm clock bug in iPhone, iPad and iPod touch running on iOS 4.2.1 (or earlier versions as well), which will cause the alarm clock to not work on the New Year 2011.
This bug will occur on your iOS device when the clock strikes midnight in your country and then one off alarm will cease to sing out.
This means that anyone who sets an alarm for tomorrow won’t be woken up by the device’s alarm clock. So to avoid this issue you simply need to create a recurring alarm at the time you need to be woken up, and then disable it once you are woken up. Or you can follow our how-to guide posted below.

According to 9to5Mac, the alarm clock bug will automatically fixes itself on January 3rd.
How To Fix Alarm Clock Bug
You can fix this alarm clock bug by following three simple steps posted below:
Step 1: Tap on ‘Clock’ then on ‘Edit’.
Step 2: Tap on your alarm then on ‘Repeat’.
Step 3: Now set a repeat interval and then ‘Save’ it.

Sweet! You just saved my iTouch from an untimely death against the wall after the 2nd morning of not waking me up!