The macbook is just like the PC in terms of Blu Ray playback. Due to licensing issues, you must purchase software that has blu ray playback/license functionality. There is no OS that i'm aware of that includes this for free due to licensing costs.
Generally speaking you can get software such as PowerDVD for windows for BR playback, but none of it is free for either OSX or Windows, and likely never will be. You must pay for the privilege, so to speak. That said, some external Blu Ray drives may include software for playback as part of the price, but most do not.