Following on from this questionthis question, what resources are available relating to the technical specifics of how apple implement encryption on their iOS 4.x series devices?
The Apple marketing material here, states that "iPad offers 256-bit AES encoding hardware-based encryption to protect all data on the device. Encryption is always enabled and cannot be disabled by users."
Using a custom RAMDisk to boot up an old iOS device it was possible to see the contents of user files in the clear which means in some way if they are encrypted the process of booting the custom OS is allowing for decryption of the data to happen.