My OH has an Iphone4 so I decided to upgrade it IOS 5 so that she could use the 'find my phone' option. Big mistake. The upgrade deleted years of work and home contacts, including email addresses and phone numbers. Apparently a backup is taken to itunes and once the upgrade is completed itunes deletes the backup without asking you. Known problem with the upgrade which you only find out about after spending hours on Google trying to find out what the fcuk happened.. Nice one Apple.