We all know Steve Jobs does not want Blu-ray to be on Macs. He famously referred to the licensing rules for Sony's format as a "bag of hurt."
Nevertheless, people do want to play movies on their Macs, and not be ripping DVDs or going to the iTunes store. With Blu-ray disks getting more popular, most computer manufacturers offer Blu-ray playback as an option.
Now, you can join the club if you have a recent Mac. Macgo is offering a software player, the first on the Mac, and you can try it free for 90 days. If you like it, it's $39.95 for what's called "a life-time version." The app also supports DVD playback. Of course you need either an external or internal Blu-ray writer that you'll need to buy and set up yourself.
I have an internal third party drive I purchased from Other World Computing, so I gave it a shot. On my Dual Core Xeon Mac Pro the app was a mixed bag. The movies I tried played, and looked great, but there was some stuttering, some macro-blocking, and a couple of flat out pauses. This happened on several movies, including Ghost Writer and the restored Once upon a Time in the West. It could be that my older hardware is the problem, or maybe the software player is just a bit flaky. There are no minimum hardware specs posted on the site.
There have been some positive results reported out there, however, so since the app is available with that 90-day trial, you can download it yourself and see how it works for you.