Mac: The Mac Blu-ray Player from Macgo will read a Blu-ray disc from an attached drive and play it in Mac OS X. It works and it's the only option currently for Blu-ray playback on the Mac, but there are tradeoffs for the convenience.
First of all, the app requires that you be online at all times while watching a movie. Macworld called the app out for this specifically and noted that while the developers cite "technical limitations" for this, the reality is that the software can decode the copy-protection on the Blu-ray disc in real time. That may not be a big deal for some people, but it definitely eliminates firing the app up on a long flight.
Still, Mac Blu-ray player seems to work, even if it's brand new and not quite polished. The price tag is $US39.99 for a "life-time version," according to Macgo, which implies there may be a subscription cost if the app takes off. You can download and try it for free for 30 days before being prompted to pay for the app.