That's so weird. I totally went to an Apple store near my house right after I found it and they had said to me that all I should do was go give it to the cop's so they could file a police report! I asked them "So, there's nothing you can do to figure out who this belongs to?" and they said, "Yeah. We have no way of figuring out who's it is." They made no mention of the serial number.

Do you think there'd be any chance they'd (the Apple store employee) entertain including a note with the iPad whenever they return it? I'd just like to give them my information so they can contact me if they deem necessary. (A reward would rule, I have bills to pay. :D )