I know this is on the ORG, but I cannot contribute to that part of the forums yet so I thought I would add my two cents here.
I think you definitely need to call up Hamilton for September if not for the playoff roster. A lot of people are arguing about burning option years, but I think he needs to be up with in the majors regardless of adding an extra option year. Look, come 2015 or 2016, who knows where this ball club will be at. They could be a similar team we have now or they could be like the Phillies.
What we do know is that our major league roster is winning now and the chemistry in there is good. Why not expose Hamilton to what we have now? We have guys like Rolen, Arroyo, and Cairo who are experienced veterans that can be big influences on the kid.
I say come Aug 31st, you have Cairo come down with some back problem and DL him. Bring up Hamilton. That way, you have him for the playoffs if needed. I also think a lot of guys are underestimating the value of a pinch runner, especially in the playoffs. If it is a close game and Rolen walks in the bottom of the 9th to lead things off. Why not bring in Hamilton to steal for scoring position or even a sacrifice fly?
Also, I think Hamilton could gain some experience at shortstop come September. Cozart is definitely our most consistent starter. He plays nearly everyday and is only a rookie. Why not give him a break once we clinch a playoff spot?