Which internal Blu-ray drives are compatible with a unibody Macbook Pro? Dimensions
The (unoffical) dimensions which I found are:

9.5mm slot load

Software
There is free Blu-ray player software available for the Mac and Toast Titanium 11 is able to burn Blu-ray discs.
As it turns out, there are only few Blu-ray drives which are compatible (dimension-wise) with a unibody MacBook Pro and the lack of Apple support for this media makes driver support, associated software and other requirements makes reliable information on using a BlueRay drive with OS X and Macs hard to come by.
Question
How can I know if a specific internal Blu-ray drives will work when installed in the unibody MacBook Pro? (both specific models you know work with specific OS answers and answers to explain this in general would be of use)
The following YouTube video by breakbeet808 confirms that

... It is now possible with the Panasonic/Matshita UJ167 9.5mm slot-loading BD-ROM drive, and/or the UJ-267 BD-Recorder drive, and some extra software: Mac Blu Ray Player from MacGo.

However, these blu-ray drives are not a &quot;100% direct swap out replacement&quot;:

There is a slight difference with some mounting points on the top side
of the drive. The problem is solved by swapping the drives' upper
casing out. (see &quot;How to upgrade to the Panasonic/Matshita UJ167 drive&quot;)

Once you finish the upgrade, OS X will &quot;recognize blu-ray discs and it will be available to the file system like any other optical disc&quot;.

How to upgrade to the Panasonic/Matshita UJ167 drive
This may void your warranty. Try this at your own risk.


Remove the original superdrive. (You can follow instructions by ifixit, for example.)
Remove the top metal shell of the drive itself, by removing its four screws. You'll also have to peel off a strip of silver tape that connects the top shell to the bottom shell. This will expose the internal guts of the superdrive. It's this top metal shell that we need to keep, it has the mounting holes in the right spots, so be very careful not to damage it. Do not touch any components inside of the drive. You may want to look up how to do this, it's a little tricky to free it up successfully.
Now remove the top metal shell of the new blu-ray drive in the same fashion.
Swap out those top metal shells, and screw the drives back together. The top metal shell from the original superdrive should now
be on the new blu-ray drive.
Now also swap out the small Y shaped mounting bracket from the plug-side of the superdrive and screw it to the new blu-ray drive - those two screw holes do match up exactly already.
Carefully unplug the flexible data connection cable from the old superdrive and plug it onto the new blu-ray drive.
Reinstall blu-ray drive.