You don't necessarily need iTunes - you can back up the iPhone to iCloud without iTunes. It doesn't let you access details of your contacts in any other way - but you can restore the iPhone and contacts if need be in future.
Go to Settings- -> iCloud -> Storage and Backup and turn 'iCloud Backup' ON.
ZeN Performance and Process Improvement Manager
15.4" MacBook Pro with Thunderbolt- raaa!
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