That depends when and where they got them.
According to reports Monday in Gizmodo and Ars Technica, citing AT&T sources, U.S. customers who bought an iPhone from Apple AAPL or AT&T T after May 27 will be allowed to trade it in for a new one with no additional charges (beyond the usual 10% restocking fee).
Customers who purchased an iPhone on or before May 27 are out of luck.
In the U.K., O2 is offering its iPhone customers a better — if more complicated — deal. You have to know what “top-ups” are to understand the terms offered on O2’s website here. It’s a little clearer as MacWorld UK explains it:
No word yet on trade-ins from Orange in France or T-Mobile in Germany.