Our friends across the pond at The Register are reporting about an issue that has been discovered surrounding Apple's much touted MobileMe trial especially when trying it for the limited time period and then canceling it.
Synchronization with MobileMe makes sure that all the devices are up-to-date regarding content, etc. However, something really bad happens "when an account is canceled; all the data is removed from the cloud, which is fine - unless the user lets their iPhone synchronize with the newly-created void. In that case they find their calendar unexpectedly clear, and a curious lack of any contacts with whom to make appointments."
This unexpected situation was reported by Register reader, Phil Blackman, "who suffered from just this problem" and did not find much help from Applecare." and it was discovered that "Apple only retains data for paying subscribers - those on the trial have lost their data forever."
The highly integrated nature of the iPhone to MobileMe is the reason for this problem; a fix would include ensuring that push services are turned off on the iPhone prior to canceling your MobileMe services. It would also be wise to back up one's personal data especially, contacts, calendar, etc. on the system used for syncing.