Change of heart? Why? I think they are doing a pretty smart move to be friendly towards open source community, but it's not because I believe they changed their mind and want to contribute to the open source world, instead, I simply believes they embrace open source community is because it's good for business.
You see, open source software these years became pretty good and infrastructural. If Microsoft can't be a part of it, then they will soon be obsolete. And they don't want to be obsolete, so they just can't afford to not be a friend with open source.
The real thing that I curious about is what would happen when Microsoft managed to re-dominates the software market (in both user and enterprise end). Will they still be friendly with open source community after that?