Microsoft has opened up a lot over the past several months. It released powerful mobile versions of Office, launched cross-platform health technology and even posted some code for .NET, the programming framework that underpins a large part of the Windows world. Today, though, the crew in Redmond is going one step further. It's open-sourcing a much larger web- and server-oriented chunk of the .NET development stack, and has revealed plans to bring an important part of that stack (.NET Core) to both Linux and the Mac in the months ahead. Yes, you read that correctly -- code that Microsoft once held extremely close to the vest will soon run on most modern operating systems.