As if the subject of this post doesn't clue you in on my initial reaction to finding out about this, I was quite surprised by the fact that .NET is now open source under the Microsoft Reference License (Ms-RL) . I'd like to see open source zealots' reactions to this one. I'm sure they'll say it's all in a move to push Windows licenses... however that might work. On a lighter side, I'm curious what the Mono folks will do with it. As I understand the license, I don't believe they can simply run with the code. Then again, it looks like they are utilizing some key components of the framework.
On the other hand, Miguel de Icaza claims the license isn't an "open source" license ; however, I'd argue this. By definition, open source is about access to source code. This doesn't mean you can use it for whatever you see fit or even contribute to it. That's why there are so many different types of open source licenses. Miguel's idea of open source seems to be more about open use, open contribution, or perhaps solely on whether or not a license has been Open Source Initiative (OSI) approved. Ms-PL hasn't, but that discussion is underway . After reading a little bit of Miguel's thoughts and opinions, it seems to be more about open contribution. I'll have to stand by the fact that this isn't and should never be the utmost important tenet to becoming "open source." I will agree that it is key to the greatest level of openness. Honestly, tho, I don't think I'd accept anything from everyone if I managed an open source project. There's just too much crappy code out there. Miguel's last comment in the aforementioned post indicates he wants it all, tho.
No matter what Miguel's thoughts of what it is to be "open," I think everyone will agree this is a fantastic move for the community. I love having source to look at. This is why Reflector has been so popular. As Miguel mentioned, I've made use of the Mono source many times when I wanted a peek into .NET. This isn't the same, but it's been close enough. I think more people will be interested in what Microsoft has written than Miguel and company... not to devalue their effort.