I've done pilates but it wasn't specifically for cyclists. It was a group class with a really good instructor who really knew her stuff - it seems to be one of those things where the teacher has a massive influence on how effective it is.
One thing to note is that it took me a few months to notice the benefits, it's definately not a quick fix. I did a class once a week and then incorporated some of the exercises into my weights routine or used them as a 10-15 minute routine after doing any running or cycling.
I have a cd and workout cards by someone called "Brooke Siler" which is quite good.