more to this than meets the eye
This whole mobileme and itunes interface is way more complex than it needs to be, with some undesired results occurring.
iTunes is the only app that does a complete back up of everything on your phone, but unfortunately it does this by Syncing which can result in duplicates in your phone afterwards of contacts for example SO:
Unplug your phone from your computer
Open iTunes
Go to iTunes preferences
Click Devices
Delete all old iPhone backups (be sure your phone has on it what you want to back up first!!)
Quit iTunes
plug phone into computer
relaunch iTunes
click iPhone icon
click Info Tab
click all the things you want backed up
click Apply
Sync starts
after this you will have duplcate contacts and calendars
Eject phone icon from iTunes
unplug phone
These next steps assume you want only ONE copy of Contacts, and ONE calendar, so check whether you have duplicates before following the steps to get rid of them. YOu should also make sure you have Synced with MobileMe (another can of worms) and that copies of your calendars on MobileMe, iCal, and your iPhone are all synced, and any entry made on one automatically updates the other THEN on your iPhone:
go to Settings>Mail, Contacts, Calendars
Delete every account except for MobileMe (.me or .mac account)
Click on the one remaining account
Turn off Contacts - choose Delete from iPhone option
this gets rid of the duplicate contacts
Turn Contacts back on - choose Merge with MobileMe option
Turn off Calendars - choose Delete from iPhone
turn Calendars back on - choose Merge with MobileMe option
Personally I think the above rigmarole is totally and ridiculously cumbersome and fraught with risk of accidental deletion/duplication, which I have personally experienced. IMHO, there should be a new application written called "iPhone" that runs on PC or Mac and that takes care of EVERY part of the phone including Syncing, Backups etc. E.g. back up - you should be able to choose from a menu anything you want to back up in either direction with replace or merge options. The concept of 'Sync' to back up data is ludicrous, because it results in all the unnecessary above steps. Moreover spreading these similar but essentially different functions across iTunes (for a phone??) and System Preferences (!!) seems designed to confuse from the start. The distinction between Syncing in iTunes and Syncing in MobileMe for example is that one is a batch process, the other is dynamic - yet both are called Sync.
In my view, this is absolutely the worst part of the iPhone interface, which otherwise promised to be a convenient easy to use device. The above info was gleaned from many hours (yes - hours over several nights and days) talking to different customer service agents from Apple at 10p per minute, sometimes after being told I would be in a queue for 10 minutes, sometimes getting conflicting information, or agents who really did not know the iPHone at all. There is also a different web based tech support system (free) but that services only MobileMe, not the iPHone - see what I mean?