An A+ in an AP class in some schools result in a 5.3 towards your GPA. A GPA on the weighted scale takes into account the difficulty of a given course. One student even managed to land a stunning 10.03 GPA by taking 17 advanced classes at a school that awarded bonus points.
Many Public schools are trying to ditch the A to F system and go more towards a standards-based grading with a pass/fail.
It is not the future, as many colleges are going away from the weigh of a GPA during admissions review taking more consideration on other areas like SAT score, essay, interview, community activism, etc.