On the surface, the Linux-deal between Microsoft and Novell was surpising. At first Microsoft tried to ignore OSS, than it tried to fight it, and now they seem to adopt it.
But it turned out to be a strategic move about patents. Microsoft claims that RedHat Linux violates dozens of their patents. By threatening RedHat users, Microsoft hopes they will migrate to Novell's SuSE Linux. They claim that in China this approach is already proving to be succesful.
To their credit, the patent-game is not the only result of this cooperation. They also work on interoperability between Microsoft and Linux environments. Which is something that could be very beneficial.