1. whether this means Microsoft is no longer the enemy of the open source movement
2. if not, then does it mean Microsoft has so lost in the web server arena that it's resorting to desperate moves.
3. or nah — it's standard Microsoft operating procedure. Embrace, extend, extinguish.
What I'd like to ask is whether anybody that's not currently a .NET fan actually wants to use it? Open source or not. What is the competition? Java? PHP? Ruby? Node.js? All of the above? Anything but Microsoft? Because as an OSS advocate, I see only one serious reason to even consider using it — standardization. Any of those competing platforms could be as good or better, but the problem is: how to get a job in this industry when there are so many massively complex platforms out there. I'm still coding in C, and at 62, will probably live out my working days doing that. But I can still remember when learning a new programming language was no big deal. Even C required learning a fairly large library to make it useful, but it's nothing compared to what's out there today. And worse, jobs (and technologies) don't last like they used to. Odds are, in a few years, you'll be starting over in yet another job where they use something else.
Employers love standardization. Choosing a standard means you can't be blamed for your choice. Choosing a standard means you can recruit young, cheap developers and actually get some output from them before they move on. Or you can outsource with some hope of success (because that's what outsourcing firms do — recruit young, cheap devs and rotate them around). To me, those are red flags — not pluses at all. But they're undeniable pluses to greedy employers. Of course, there's much more to being an effective developer than knowing the platform so you can be easily slotted in to a project. But try telling that to the private equity guys running too much of the show these days.
So, assuming Microsoft is sincere about this open source move,
1. Is .NET up to the job?
2. Is there an open source choice today that's popular enough to be considered the standard that employers would like?
3. If the answer to 1 is yes and 2 is no, make the argument for avoiding .NET.