I have the same problem.
I ran the osx installer, and got the latest patch, but when I run the game it makes no effort and says failed to load. I even used the diablo no cd trick
(see here
http://www.insidemacgames.com/news/story.php?ID=16662)
and still no luck...
Seems to me like its not even trying, the disk never even spins nor does the fan speed increase
So my guess would be programing bug with desperate need of blizzard patch 112b
anywhoo let me know if anything changes
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Solution
Blizzard Release Diablo 3
oh wait... this will never happen...