I did have success once with sending an e-mail to tcook@apple.com. I have read that like Steve, he does read many of those external e-mails.

This was when the App Store review times had climbed to 28+ days. I never did get a response, but shortly thereafter they started going down, and within a few weeks were down to the 3-7 day range. I don't think they've gone significantly over 7 days since.