Considering that monitors display at 60 hz, the only real framerate is either 60 or 30. More than 60 will produce tearing and anything under 60 will force the monitor to display a double image and wait for the next refresh essentially putting it at 30 fps. There is no 59 or 61 or what have you. If the game slows down it will temporatily go to 30, which is noticeable.
Without any real scientific tests done on bb with ps3 -which i haven't seen any of- its all speculation.