According to MacRumors, Apple will completely change how the serial numbers for Macs are generated. The numbers will soon be fully randomized, meaning that users, IT managers, repair-shop technicians, and others will not be able to glean the same information from them that the current serial number system provides.
Serial numbers on Macs shipping today reflect the time and place where the Mac was assembled, as well as some configuration details like storage capacity. Moving forward, serial numbers will be fully random, with no code or consistency that can be used to learn information about the product. The new numbers will be between eight and 14 characters long.
MacRumors claims it learned of the change when it gained access to an internal AppleCare email. This change does not apply to Mac models that are shipping today, but it will go into effect for future Macs the company will introduce. That includes the rumored MacBook Air, MacBook Pro, and iMac refreshes expected later this year, as well as new Mac Pro models that appear to be planned for a later date.