The countersuit says that "Microsoft is misusing these patents as part of a scheme to try to eliminate or marginalize the competition to its own Windows Phone 7 mobile device operating system posed by the open source Android operating system and other open source operating systems."
At this risk of sounding cynical, isn't that typically why large mobile companies sue one another? The field is growing so quickly, and with so much overlap and acquisitions, that it's hard to say who's misusing which patent.
But despite our cynicism, we do think that Microsoft might have to back down on this one. Particularly with their reputation for allegedly monopolistic practices, a judge might be quick to believe that the Redmond giant is unfairly putting the squeeze on 'smaller' companies.