In the open source community many are doubting Microsoft's intentions in open sourcing their crown jewel. They frankly don't know what they will do with themselves without Microsoft to vilify .
Steve Ballmer in announcing the bold move said that Microsoft finally realized trying to enforce licensing against pirated copies of Windows used in many parts of the world was just a losing proposition. Also the constant battles with the Linux community, while Apple was outflanking them on new platforms, was sapping the company of creativity and energy. Ballmer said this about the competition from the open source community, "if you can't beat'em, join'em".
The open source licensing applies only to Windows, not Windows mobile or X-box or other Microsoft software.
Of course not all Microsoft officials are behind the move. Bill Gates reportedly is hiding out at Warren Buffet's modest house in Omaha, NE trying to understand what went wrong. Microsoft's other co-founder, Paul Allen said he knew this would eventually happen. He reportedly wanted to do this years ago, but Ballmer and Gates forced him out instead.
In the meantime, the move has caught Red Hat flat-footed. Just when they reached a billion dollars in revenue, it appears their market share could plummet. They are counting on the Microsoft hatred in the community to keep people using RHEL. They know that even with Windows open sourced, there will be many who hate Microsoft anyway.
Also in the announcement, Microsoft said they will drop any patent claims against Linux, seeing as how Windows is now open sourced anyway.
In the analyst community, reaction was mixed. Many have been calling for Microsoft to do something big and bold in open source. But frankly no one expected this. Other's think this is only the first shoe and must be part of a larger diabolical plot from Redmond. One analyst wrote on Linux.com, "Microsoft doesn't give away ice in the winter, they wouldn't do this unless they had something else in mind".
So what will the world look like with Windows open source? I don't know but it sure would be fun to think about. HAPPY APRIL FOOLS DAY!