We started experiencing this problem on all Apple iPad, iPhone & iTouch platforms when we migrated our Microsoft Exchange to 2010. We have been able to duplicate it on all carriers also. Verizon, ATT, Sprint & T-mobile have had the same issue. It appears to only be affecting a "multi-day" appointment and what we have seen is similar to what is being posted, but ours not only moves it out a day, but also moves the original appointment out 1 hour. I have received several solutions that work, but are not fixes to the problem.
1) In escalation with Apple we were told to create the appointment from the device and not from Outlook. That did
correct the problem with the specific event, but it would have to be done for each "multi-day" appointment.
2) In escalation with Microsoft we were told to create the appointment in Outlook and not have it span more than 1 day.
So if a person wants to create a week of vacation it would have to be done in (5) separate events.
Its a wierd issue, because I have read many different responses to this and there doesn't seem to be any consistency with them. I have read where people who used Exchange 2007 and had the issue, then migrated to Exchange 2010 and it went away. I have read where people like us who never had the issue in 2007, then migrated to 2010, started seeing the issue.