Today, the US judge will decide if Microsoft's Xbox infringes on Motorola's Wifi and video codec patents. We've already had a ruling in Germany stating that Microsoft should pay Google because they infringed their patents, but they couldn't put an injunction on Microsoft's Xbox until the US judge took a decision.
Now Microsoft risks paying Google $4 billion per year in royalties, because they were foolish and greedy enough to go after companies using open source software like Linux and ChromeOS. Microsoft has never been shy about crushing the little guy in the past, and it's one of the reason why they got into so much trouble with the anti-trust lawsuit. Plus, they just don't like the open source movement too much as their competitor.
Now, Google is not exactly a little guy, but they never went after Google themselves. They first started asking for royalties for secret and most likely very weak and broad patents from the smaller companies, like HTC, and then they start moving on to others. It's a lot easier to extort money from one company when you show it a list of other companies that agreed to pay to get them off their backs, and that's exactly the strategy that Microsoft used to get all these companies to pay them royalties - all for patents that have never been tested in Court..
If they were tested in Court, like with Microsoft's lawsuit against Motorola where Microsoft lost 6 out of 7 patents because they were invalidated for being useless, Microsoft wouldn't be able to use them against anyone. It's just too bad that not many manufacturers have the courage to take Microsoft to Court. The only one that did, B&N, would've won, and to stop that from happening Microsoft gave them a nice amount of $300 million as investment in the Nook division.
Google says that they didn't start this, and it's true. Microsoft went on the offensive first, and not they are whining that Motorola wants to charge them a too high amount. Well, if they want, they could always drop all royalties from the Android and Chromebook manufacturers (which are an order of magnitude smaller than what Google wants them to pay anyway), and I'm sure Google will settle so they don't have to pay them anymore. If they don't, and depending on the decision today, Microsoft might see its Xbox blocked from being sold in the US and also in Germany.