Just to bring the thread back up to date, I think we finally got our game here guys! I was reading announcements this morning on the Steam phone app, and read where they're having a mid-week madness of Dead Island, to celebrate the arrival of the Mac version. 75% off, which is $4.99.
It could be an April Fool's joke, but it says the deal is good through April 4th. The Steam program on my Mac reflects the sale, and clicking on it for details gives conflicting data: it still only shows the Windows logo, but further down the page gives Mac minimum requirements
"OS: OS X 10.8 and newer
Processor: Intel Core i5 2.7 GHz
Memory: 8 GB RAM
Graphics: NVidia GeForce GT 640M 512MB"
Can anyone who's bought the game already for Windows confirm that it can be downloaded and played in OSX?