Cupertino has been known to share a stat or two during its WWDC keynotes, so it's hardly a surprise that the company just dropped some sales figures for its Mountain Lion. According to Tim Cook, 28 million copies of the OS have shipped, making it the best-selling Mac release of all time. Cook also said that about 35 percent of users have updated, compared to less than five percent for Windows 8. Of course, Apple wasn'