iTunes will back up the following information:
* Safari bookmarks, cookies, history, and currently open pages
* Map bookmarks, recent searches, and the current location displayed in Maps
* Application settings, preferences, and data
* Address Book and Address Book favorites
* Calendar accounts
* Wallpapers
* Notes
* Call history
* Mail accounts
* YouTube bookmarks
* SMS messages
* Saved suggestion corrections (these are saved automatically as you reject suggested corrections)
* Camera roll (photos and screen shots taken by the iPhone)
* Voicemail token (this is not the Voicemail password, but is used for validation when connecting. This is only restored to a phone with the same phone number on the SIM card.)
* Web clips
* Network settings (saved wifi spots, VPN settings, network preferences)
* Paired Bluetooth devices (which can only be used if restored to the same phone that did the backup)
* Keychain (this includes email account passwords, Wi-Fi passwords, and passwords you enter into websites and some other applications. The keychain can only be restored from backup to the same iPhone or iPod touch. If you are restoring to a new device, you will need to fill in these passwords again.)
* Managed Configurations/Profiles
* List of External Sync Sources (Mobile Me, Exchange ActiveSync)
* Microsoft Exchange account configurations
* Nike + iPod saved workouts and settings
* App Store Application data (except the Application itself, its tmp and Caches folder).
* Videos in camera roll
* Per app preferences allowing use of location services
* Offline web application cache/database
* Voice memos
* Autofill for web pages
* Trusted hosts that have certificates that cannot be verified
* Web sites approved to get the location of the device
* In-app purchases
* Videos in the camera roll that are 2 GB or larger are not backed up.