http://espn.go.com/mlb/story/_/id/76...-put-hold-2013
For anyone who cares, instant replay wont be expanded until next season. They don't want everything reviewable, just fair/foul down the line, catch/trap, and fan interference everywhere (not just for home runs).
There were basically 3 sticking points to work out for 2013. First, who asks for a challenge and how is it resolved? A manager, or someone in the booth? Would the umpires view the replay and make the call, or do you do it like NHL where a replay official tells everyone to stop, then he quickly looks at it right in his booth and makes the call? Second, the umpires want MLB to upgrade the video replay in all stadiums, apparently the replay equipment in some stadiums is a lot better with more angles on the field than others. Finally, the umpires union wants something in return for agreeing to this. Either higher pensions or a 7th man in the playoff crews (center field ump?) so more umpires get to experience the postseason.