But who gets the most out of this ?
Now, before this comment is picked up as being solely cynical or negative... No, I applaud this development because IMO this is a step in the right direction. After all; at the very least do we get a little more insight in the software which Microsoft has provided us with in the last few years which I think is good.
Another reason why I consider this a good development is because its a somewhat logical step. I mean; their development environments (talking about their Visual Studio 2010 for Web development here) have been available in a free ('Express') form for quite some time now. So if you want to get your hands on the ASP Web API you could. Simple. As such its IMO only logical to open things up a little more. And who knows what might follow ?
However, I do have to wonder if MS doesn't get the better end of the deal here (of course they do this for a reason of their own as well, sure).
You can pick up the source code to the Web API (which is basically a framework) but then what? While you can pick up an ASP 'container' (IIS) for free as well, it doesn't give you the amount of freedom you'd have if you could also get access to the source code of the underlying engine. So then I start to wonder how others may benefit from this, also considering that this is basically a framework build on top of ASP.NET which remains closed.
I know about stuff such as mod_mono or Apache::ASP but even then I have some doubts if this API will / could be beneficial there. Because that is IMO one of the boons of open source; the ability to pick something up and utilize it in totally different ways. Yet I don't think that will really apply here (though I could be wrong of course).
So; not to sound ungrateful or anything. IMO this is an admirable step in the right direction, I think we can all benefit in the end with a more transparent Microsoft, but in this case I do have some doubts.