MLB teams are now allowed to use the iPad in the dugout, but there are still some restrictions for who the tablets can be used. Recently, the Apple Watch was approved for use in the dugout by the MLB, so this is just yet another piece of technology that is being added. The restrictions for the iPad are a bit odd, but this is likely just an entry point of getting the technology introduced, and in an effort to keep things as fair as possible.
Each day, the teams are able to decide what information they want loaded onto the iPad, and they can't have PDFs, videos, or anything that could allow for information to be relayed in real time. The home screen of the iPad is also cleaned so that only access points to the data are seen. The iPads are given to the team in a steel security box, which can be opened before the game. From NJ.com:
Still, just how much the iPad can really help will still be determined. Already, baseball teams have access to video and information during a game. Players regularly duck into the tunnel during games to look at video during innings in a room located just dozens of feet away.
More likely is that the iPad becomes an entry point for Major League Baseball to assimilate more technology into the game somehow.
The iPads are returned each night after the game to the game officials, and the iPad is then scrubbed. For the next game, the process starts over again. Though the teams have previously had access to much of the same information that the iPad brings for years, its interesting to see technology replacing the old big binders that teams previously kept in the dugout.