Upon (my own) careful observation, and with great respect for tilly, I still feel the need to point out that this portion of the license doesn't contain anything unusual.

Its intent is clear:

• Prevent anyone from getting the impression that MS will provide support for the GPL'd or GPL-like portion of a product developed with the SDK + Free Software. ("create, or purport to create, obligations for Microsoft with respect to the Software"). It's easy to be mislead and think that if 90% of a product is pure MS, and 10% of it is something you're "not to sure about", that most likely MS must be supporting that too, which again, they clearly state they don't. And why blame them? Perl is not their baby, if they don't want to support it (or ANY software that they didn't make, regardless of the license), then who cares?
  
  
• Prevent anyone from thinking that MS should give them their source code for the SDK, just because other portions of a work that use the SDK are written using tools that do happen to provide their source code. ("grant, or purport to grant, to any third party any rights to or immunities under Microsoft's intellectual property or proprietary rights in the Software.") Nobody here needs to be reminded of how stupid users can be, and the misconception that "hmmmmm...I have full source code for this part of the program, but not that part...I should phone MS and get what is rightfully mine!" could easily become commonplace.

From the GPL FAQ:

I am writing free software that uses non-free libraries. What legal issues come up if I use the GPL?

If the libraries that you link with falls within the following exception in the GPL:

However, as a special exception, the source code distributed need not include anything that is normally distributed (in either source or binary form) with the major components (compiler, kernel, and so on) of the operating system on which the executable runs, unless that component itself accompanies the executable.

Clearly, the Microsoft Mobile Internet Toolkit is not a "major component of the operating system", and so the potential licensing conflicts are easy to spot, and therefore the license (as any license on any product) does what it needs to do to cover the ass of the person that wrote it.

To argue that "proprietary software just stinks" is a whole other issue entirely, and doesn't take any special form of intelligence to realize that there will probably never be a "right" answer to that debate. For anyone who feels that they stand on the moral high-ground, and actually "knows" the Right Answer (TM) to this, please let me know whether abortion, the death penalty, and smoking mirjuana should be legal too. And while you're at it, cut my taxes in half.

To argue that "yeah...well MS just fears Free Software!" is silly too. Why is anyone surprised that a company is trying to put out negative propaganda about their competitors? The concept of "trying to make yourself sound better than your competitors by making them sound like crap" is nothing new, and predates computers...even predates electricity. :) I, for one, would find it much more confusing if MS promoted how "good Linux is". That would be like the Pizza Hut Delivery boy coming to your door and saying, "next time, you really should order from Domino's, they're way better than us!".

To make any other argument without specific, cited evidence to support your position will certainly not get any of my consideration. I've done the research, so if you think I'm wrong, SHOW ME why I'm wrong, don't just tell me.

Admittedly, the term "Viral Software" is an insult (they could have chosen so many other ways to describe it than that), but then, that wasn't the point of this thread. If it was, I wouldn't have done the research to provide this response.

Perhaps you should ask the authors of the GPL to modify the license so that there's no restrictions on linking to non-free software.