I confirm the exact same problem reported by user 5pence5, even with the updated version released mac beta shank 2, 2012-12-28. It crashes immediately when selecting a difficulty from campaign; screen goes dark then back to desktop and moments later it indicates that "shank2 quit unexpectedly".
http://pastebin.com/XJ5aXaFD
Mac specs: 8GB RAM, 2GHz Core i7, OSX 10.7.5
Really excited to see this on mac