Apple will be offering an in-store trade-in program for iPhones in the U.S.. We're not sure if its happening everywhere else, but the program complements Apple's existing online effort, which gets you a gift card in exchange for your old phone.
Apple has reportedly confirmed the program, and according to CNBC the new program requires that you sign up for a new carrier contract and that you'll have to put whatever credit Apple offers you to the purchase of the new device.