I'm playing mostly Good but i can't resist chasing down civilians and stealing their blast shards. I was wondering though, since there are a set number of shards in the world what happens when you steal one? Or does this game handle collectables differently than most open world games?

It doesn't matter. There is a finite number but the number is really high. I did two play throughs on good and evil and you can max out the karma meter at some point. After that point I went crazy stealing as many shards as I wanted. Just make sure to constantly balance it with good deeds. After a while I found it a pain in the ass to chase the runners down. It was easier to wait for the random events where you diffuse a bomb for a shard.

I remember in the first game you could max out the meter with the collectibles on the map but you could reach the max faster by getting shards from quests. I think it's the same in Infamous 2. Once it's maxed instead of saying how many shards are needed to upgrade it should say how many shards remain to be found.

@djou: I just used the electric whip to trip em up then restrain em and steal their shards.