Effective April 3rd, 2017, guests parking at Magic Kingdom will go through metal detectors and have their bags searched at the Transportation & Ticket Center. The security checkpoint will be required before guests can access the Monorail or Ferry Boat systems. Guests arriving by bus will still go through a security checkpoint in front of the Magic Kingdom. The only alteration we see for bus riders thus far is that security tents have been set up closer to the bus stops.
In addition to the changes above, the three Disney Resorts that have Monorail stops (Polynesian Resort, Contemporary Resort, and Grand Floridian) will have added security checkpoints before you can get on the Monorail to travel to the parks.
These measures not only protect travelers on the Monorail, but it alleviates some of the congestion guests feel while trying to enter the Magic Kingdom. The only unfortunate side effect of this new procedure will be that resort hopping will be a little more tedious and time consuming than it has been in the past.