The Federal Patent Court in Germany, a country that's usually very friendly towards patents, has invalidated Microsoft's FAT patent, which was by far the most important weapon in Microsoft's arsenal against Android OEMs, especially after Barnes & Noble almost destroyed their other "important" patents that they were using against Android manufacturers, in their lawsuit with Microsoft, thanks to a ton of evidence for prior art.
Unfortunately, at the time, Microsoft offered $300 million to B&N as settlement (they called it an "investment" back then), and the trial ended, leaving other Android OEMs still in limbo regarding Microsoft's patents. Soon after that, Microsoft managed to sign a deal with Samsung. What was in that deal we'll never know, but I find it very hard to believe that Samsung, who's been fighting Apple so fearlessly in their patent war, would just lay down for Microsoft so easily – unless, of course, the deal actually favored Samsung, rather than hurt them.
Why would Microsoft do such a deal? Because they knew that if Samsung "falls" (at least in the eyes of the public), every other OEM will soon fall, and pay up, too, which is exactly what ended up happening. Most OEMs quickly signed the deals with Microsoft and accepted to pay them, without even a hint that they'd rather take them to Court.
Going back to the FAT patent, which Microoft has used last year to ban some of Motorola's handsets in Germany, is clearly the most important tool they're using to force OEMs to pay up, considering Google and Motorola can still build Android devices unaffected by Microsoft, as long as they don't use microSD cards that use the FAT file system. There are options around that, such as using Samsung's open source implementation of exFAT, but at this point I think Google prefers it this way, so people get used to putting their stuff in their cloud (something I'm not actually a big fan of, because I prefer storing my stuff locally).
Plus, with FAT invalidated thanks prior art from Linus Torvalds, the creator of Linux, all OEMs could soon use FAT-based microSDs without paying Microsoft a dime on that, and they could let expire whatever deal they have for the other patents, too. Now is the best time for other OEMs to stop paying Microsoft for using an open source operating system, and it's on us to ask them to fight in our name, too, because everytime an Android OEM is paying Microsoft for an illegitimate patent (like FAT seems to be due to prior art), they are making us pay more for the devices, when we shouldn't have to.
I think either way, it's only a matter of time before this whole scheme of Microsoft of making free billions of dollars every year by extorting money from manufacturers using open source operating systems, is going to fall apart.