Wine is an Open Source implementation of the Windows API on top of X, OpenGL, and Unix. Think of Wine as a compatibility layer for running Windows programs. Wine does not require Microsoft Windows, as it is a completely free alternative implementation of the Windows API consisting of 100% non-Microsoft code
So does Microsoft fear someone making a clone of Windows?
No; to M$, a clone would be like a pirated copy– they’d find a way to make money on it eventually; in the case of Wine or a derivative, likely by extorting money from (corporate and government) users via the threat of patent lawsuits. Also, a clone would always be playing catch-up to M$; they would still fully control the direction things were going and it likely would never be 100% perfect; programs written for Windows would still work best in Windows. What they fear is the bridge it would build for users to migrate to “a different operating system“. In “a memo written for Microsoft Chairman Bill Gates by C++ General Manager Aaron Contorer in 1997″, the latter wrote:
The Windows API is so broad, so deep and so functional that most ISVs (independent software vendors) would be crazy not to use it. And it is so deeply embedded in the source code of many Windows apps that there is a huge switching cost to using a different operating system, instead […] It is this switching cost that has given the customers the patience to stick with Windows through all our mistakes, our buggy drivers, our high TCO [total cost of ownership], our lack of a sexy vision, at times, and many other difficulties […] Customers constantly evaluate other desktop platforms, [but] it would be so much work to move over that they hope we just improve Windows rather than force them to move […] In short, without this exclusive franchise, called the Windows API, we would have been dead a long time ago.
(emphasis added; note BTW that M$ tends to destroy old e-mails to avoid leaks like this)
So what we have here is a great example of how Microsoft can only really thrive where they create vendor lock-in. Great for Microsoft… not so great for you.