I see that Swiss-Ball tossing "core strength" stuff going on at my gym too. Espicially this one trainer specializing in housewives and older folk. He's got them jumping up on a step while he throws them the ball and then back down and up and it looks like he is training dogs to fetch. Sadly, one old bird last week must have missed the jump 'cause I heard a crash and looked over and the old lady is down, the swiss ball is rolling across the floor towards wall and trainer-boy is trying to help her up whilst explaining that she totally messed up the excercise and he might need to seek therapy over the incident......jeezus.
Keeps them away from the free weights though. I always have the squat rack to myself on leg days so it's good for me.