Apple's Reuse and Recycling program allows customers to quickly trade in their old iPhone for in-store credit when they are buying a new iPhone. Previously the amount a customer could get for their old phone would be impacted by whether or not the phone had water damage. If the iPhone's liquid contact indicator was activated, the iPhone would be worthless (for Apple's trade-in program). Now, however, iPhones with liquid contact indicators that have been activated, but that are still in working order, will still be accepted for the trade-in program.
As 9to5Mac notes, the iPhones still cannot have any serious water damage, including liquid under the iPhone's display, or corrosion in any of its ports. The changes are good news to those iPhone owners who wish to trade them in and may have fully functioning iPhones whose liquid contact indicator was only activated due to, for example, sweat while working out.