I'm not sure "open" is the idea I'm going for here, rather OSX exposes a larger existing ecosystem of tools, libraries, applications, all of which are open source. Now the topic of the original article was about a closed environment versus an open one, and it certainly seems to me that since OSX is unix, that it's part of a larger, open environment, and I think that's why their desktop market share has increased since OS9 and below.