As I was getting ready for CES, the hard drive in my MacBook Pro died. I took the laptop (under warranty) to the Apple Store, and, mindful of Dave Winer's Hard Drive Adventure, requested that the defective drive be returned to me "because it had secure data on it". The Apple guy was surprised, but he included the words "return original drive" on the repair tag. Three days later I picked up the working laptop and the defective drive. No charge!
I suspect that as long as you confirm that the Apple Store person documents that you want your drive back on the repair tag, you should be ok.
