Apparently this is true enough, with the added qualification that for the first year or so it was largely secret from Apple too. :) http://www.theregister.co.uk/2012/06/11/apple_project_markla... http://www.quora.com/Apple-company/How-does-Apple-keep-secre... (Though of course the fact that the OS X codebase had been kept cleanly portable was neither one person's secret project nor a matter of chance.)