There is a bug in iPhone when synching to meeting of the type 'yearly on the 1st Thursday of July' starting on 07/07/2011. This can be verified with the following steps.
1. Create an appointment for the 1st Thursday in the month of July repeating yearly starting on 07/07/2011.
2. Synchronise Outlook with iPhone
3. In Outlook, roll forward to July 2012 and the appointment is correctly shown as 5th July 2012
4. On iPhone, the appointment is incorrectly shown as Saturday 7th July 2012
I have tried to alert Apple via the user forum but no response