All 30 Major League clubs have voted in favor of expanded replay on Thursday. It will be in effect for the 2014 season and postseason, the league announced following the conclusion of the quarterly owners meetings.
Replay will be used during some televised Spring Training games to educate the players, umpires, and managers of the system. That will be something to watch as baseball gets closer to it's beginning.
Replays will be reviewed at MLB headquarters at the Replay Command Center in New York. There will be Major League umpires reviewing the plays with angles that aren't just televised. The Crew Chief and one other Major League Umpire will communicate with the Command Center via headset. Then they will decide how the call will be made.
Something to note is that managers will receive one challenge. If a manager's challenge overturns any portion of a specific play, they will receive another challenge opportunity. They can only challenge a maximum of two times. Umpires can call for replays themselves after the seventh inning if the manager does not have any challenges remaining.
One other thing to note is that scoreboard will be allowed to show replays of any close play, regardless of whether the play is under review.
Here is the MLB press release that discusses the protocol of the new replay system:
The following play types will be subject to review:
INITIATION OF INSTANT REPLAY