LG GGC-H20L works, plays fine... installation is a bit tricky, and ultimately you'll need an enclosure to use it for now.
#1 To play in Windows you need AnyDVD HD to strip regional code, PowerDVD to play it (yes you can rip data to a drive etc., it's a pain)
#2 OWC does not include decent cables, simply get the cable-less one for $10 cheaper (they sent me an L-shaped SATA data cable, 90 degrees in wrong direction and a foot too long, and no SATA-IDE power adaptor) Remember to remove the bezel on the front of the drive, it won't fit through the front slot on the Mac Pro otherwise. I'm not sure if they include instructions with the cable-less version... there's probably better instructions elsewhere the fiery print-out they included was quasi-helpful.
#3 Using the SATA connection behind the fan, OS X will see the drive but Windows will not without Ubuntu ninja skillz, which are documented elsewhere. SATA IDE adaptor also will not work, unless it's specifically designed to port Bluray information. I got one for $5 off ebay, and all it did was make the drive read as a CD-ROM, not even a DVD player. So discs will not be recognized. If you are willing to give up a HD slot, you can run a SATA male to female cable directly, and that does work perfectly. Otherwise, until Mac supports BluRay MOVIE PLAYING... the best option is an enclosure for $30-40 (5.25" SATA USB 2) which are fast enough to handle data transfer.
The advantage is you will have a HD-DVD/Bluray combo player, and also a DVD 16x burner, which is way faster than a superdrive... and eventually BR movies will be supported so you won't even need Windows to play them, and then just sell the enclosure. If you are willing to wait though, by the time Apple supports it, internal Bluray players will be about $50. The LG was $300 last January, so it's seriously dropped in price in less than 12 months.