It looks like they've started their big Open initiative after they found a business case for it with Windows Azure where almost everything OSS'ed in recent time

It looks like they've started their big Open initiative after they found a business case for it with Windows Azure where almost everything OSS'ed in recent times runs on it. When you're a cloud provider it makes sense to appear "more open" and support as many technologies as possible == more customers - which is good from the broad developer community as we would have never have seen their node.js on Windows support otherwise.