Bill Hilf, Microsoft open source expert, said recently in an interview to InformationWeek that suing open source is still an option:
"Would we or could we ever litigate, yeah sure, it's always an option," says Hilf.
Microsoft tactic is to divide and conquer, arguing that the issue is about quality, and not about subject matter:
The key to that is to separate people's, individuals' and groups' belief about software patents as an issue and then what is the current way that we do patent law in at least the United States. You may disagree with it, but there's a law for how we deal with patents. They often get wrapped up together as the same issue, but they're not the same.
Microsoft wants to have the advantages of excluding competitors but not the disadvantages of the harmful effects made by software patents. Have you seen many trolls in the pharmaceutical sector?