iPod/iPhone drive/memory encryption?

I was thinking about this tonight and already submitted this idea through the feedback form at Apple.com.

I know those of us who use Macs can just create encrypted disk images and throw those on our iPod. And there is similar software available for Windows.

But why not have full disk encryption an option that is built-in to the iPod? It could be completely optional, so people can choose whether or not to take whatever performance hit it might provide.

It could work just like full drive encryption on standard HDD. You could setup a password that is required to access the iPod when it comes out of sleep or boots up. Or you could "lock" the iPod like you can now with the Screen Lock or the button on the iPhone and iPod touch.

Most importantly, there would even be an option to require a password on the iPod when it is connected to a USB port. Instead of automatically connecting to the computer and giving full access to the drive, the iPod would require the user to input the password on the iPod before connecting and giving the computer access.

Of course, there would be preferences on the iPod/iPhone that allow you to set how and when you require passwords and things like that.

But I think its a good idea. What does everyone else think? I think it would be a great deterrent against theft as well as being a great way to protect ALL of the data on the drive. It'd help against people trying to snoop, and give those of us who like privacy a great peace of mind.