"I can't find more up-to-date details but one article citing statistics from December 2009 shows OS X having five times the share of Linux."
Amongst developers, or everybody? Because in the Java dev world, almost everyone I know runs Linux.
Though it will be two laptops for one of our team, who recently got a Mac so he could do some iPhone stuff, but still codes Java with the rest of us. Good ol' Apple. Less functionality is better for you. Diversity is bad. Be the same as the rest. Jooiiinn uuussss....