Short bio: Computer Scientist, FOSS supporter (read more)
Tux Machines (TM)-specific
In November of 2006, Microsoft entered into a patent covenant and interoperability deal with Novell. In 2011, Microsoft has renewed and extended that deal to SUSE Linux, which was spun off from Novell as part of Attachmate's $2.2 billion acquisition of the company.
Across the last five years, Microsoft has acquired over $300 million worth of SUSE Linux Enterprise Server (SLES) subscriptions for resale and now has the option for an additional $100 million with SUSE. The Microsoft Novell deal shocked the Linux world at the time it was announced and potentially represented a risk to others in the Linux market.
As it turns out, five years later, it's a risk that hasn't affected SUSE Linux's rival, Red Hat all that much, if at all.