MLB Instant Replay - by end of August?

Bud Selig was opposed to Major League Baseball implementing instant replay. However, after several controversial calls at the beginning of the season, baseball could have instant replay by the end of the month.

Major League Baseball is working out technical issues to start instant replay for boundary calls such as home runs, hoping to institute the system later this year.

"We've got lots of time in August," Bob DuPuy, the sport's chief operating officer, said Wednesday as a two-day owners' meeting began. "There's plenty of August still to go."

I'm a big proponent of instant replay. If it's relatively easy to get a call right (either 1st attempt or after correction), why not utilize replay?