I have a question about GPL with regard to the above, but I'll get back to that in a minute.

I see it as extremetly unlikely that MS would adopt anything that would make any portion of their software open source. If they were to go this direction, I see it more like what Apple did with OS X - finding a way to incorporate BSD Unix into the OS without compromising their proprietary rights. I also think it's unlikely that MS would go with anything that could be made compatible with OS X. So, assuming that it did move in the direction of Linux, I suspect that they would more likely develop their own Linux-style OS, rather than using the actual Linux kernel. They might even make it compatible with Linux. The nature of open-source being what it is, developers will be motivated to ensure that subsequent developments of open source Linux would be compatible with the Microsoft beast, and MS's version would evolve into the de facto standard, thereby rendering Linux irrelevant to anyone other than the hard-core masochists and rebels who enjoy dealing with BASH. Sooner or later, MS could then pull a SCO, and allege that some subsequent development of Linux incorporated their proprietary code. Of course the opposite could not happen, because of GPL.

So, I know that if you use GPL code in a product, your product becomes subject to GPL. But what if you simply use GPL code to get ideas for writing your own proprietary code,, without actually copying it? I know that with copyrighted code, even the mere exposure to it during the development process of your own software will be the kiss of death. Is that true for exposure to GPL code? If not, I bet that's what they would do.

MS bought Q-DOS after claiming it as their own. Later they wrote the Windows shell. Win 95 was a real development, as was NT. Now that NT variants and their predecessors are recognized to be so flawed, and Linux is recognized, even by people who hate it, as rock solid, I can't imagine that MS would start from scratch with developing a new and original kernel/OS. OTOH, they've got to be really tired of polishing their existing turd.