While the 17 game/18 week regular season has yet to be implemented, the NFL has changed a few rules starting in the 2012 season. For one, all turnovers will be automatically reviewed from the upstairs booth official prior to the next snap. This will be much the same as how all scoring plays are automatically reviewed. Looks like there will be a lot fewer challenges this year, which will help speed the game up to be honest and assure accurate calls on the field the first time.
The second change is one that has been asked for for years; teams can no longer win an overtime game with a first-possession field goal. This is the current rule for playoff games, but will now be active during all games. Aside from a first-possession field goal, however, games can still be won with a touchdown on the first possession or a field goal on any other (sudden death). Changes can still be made, but this is a welcome change.
Via The 700 Level