Alarm for 6:30 worked, Alarm for 7:00 also did.
But the 7:30 did not go off.
I presume this to be related when the alarms where set. I think I added the 7:30 a long long time before and the 6:30, 7:00 just more recently.
Actually I seldom add new alarms, but rather change existing ones (i.e. change one from 7:00 -> 8:00) or something like this. I expect this to work as the function to do it is there.
I would also expect this is not an issue (until another BUG date) when you set alarm now, but like i wrote the bug might be related to a strange interference with:
+ how 'old' the alarm is (how long before it was created)
+ how often it was changed/updated
+ is the day 'special' today (DST change, New Year, Steve's Birthday)
I have a factory unlocked (from Hongkong) iPhone 4, 32 GB, 4.2.1, non Jailbreaked.
So Apple time to role-out 4.2.2 with the Clock App thoroughly tested!
I will keep an eye on my 7:30 Alarm and not touch it.