I was under the impression that not all user data is encrypted on an iOS 4 device, mainly just the user data of apps from Apple that are included with the device.
Does Apple's iOS provide for encryption of all user data? Or is it the case that the app's developer has to avail himself of an API to make this happen?
Correct, although Apple does provide an API to use the hardware encryption. Most apps do NOT use it.
If you're paranoid, you can make most data reasonably secure by using the built-in apps and apps like StashPro (which does use the hardware crypto API). This includes putting a decent length password, which is also hard to use.
Full-device encryption backed by hardware would be really great. IIRC, that's not possible on either iOS or Android right now (not sure about other platforms).
Does Apple's iOS provide for encryption of all user data? Or is it the case that the app's developer has to avail himself of an API to make this happen?