What do you mean when you say a platform is closed?
On the many mailing lists I subscribe to I too often hear that the Mac OS is a closed platform. I usually calm myself down and repeat the mantra, “He’s prolly a Linux user.” I think our two groups have very different meanings for the word open.
I wish we could come together on this issue. If the APIs to a platform are available, without the need to pony up cash, then the platform should be considered “open” by all. I know the Mac OS falls under this definition.
I do understand the Free Software Foundations concept of free. Since you can also download the source code to the core of Mac OS X, called Darwin, it is even more Free than Windows. But since almost no one has ever recompiled their Mac OS X kernel from the darwin sources it is not as Free as Linux.