NIST has released Special Publication 800-132: Recommendation for Password-Based Key Derivation which is meant for protection of stored data using encryption keys derived from user password. This seems to be the ideal method (FIPS140-2 Approved) for protecting user data on cell phones, as the encryption key is tied into the user password, thus decryption is only possible with user disclosing his/her password (nobody, including cell phone/cell phone OS manufacturer can decrypt user data if user does not disclose the password). Do you know of an cell phone OS (Android, iPhone OS, Symbian, other) that plans to implement this data protection mechanism?
It seems that current user data protection mechanisms implemented on iPhone iOS 4 are sub-par.