As mentioned above, yes Apple still does in store trade ins for Macs. My friend just did it over the weekend. She ordered her MBP without selecting trade in. Once it arrived, she took her old machine to Apple and was in and out in 5 minutes. They refunded the amount to her CC.Good grief. What the hell was I reading? Too much booze I guess?!?
From my understanding, you must do it within 14 days of purchasing the new machine (or 14 days of receiving from an online order).