Microsoft's claim is that Android and Chrome OS violate publicly-unspecified Microsoft patents and companies that are choosing to build products around these Google operating systems are making a risky bet.
Microsoft has convinced a number of Android and Linux-based device makers that it's better and cheaper to pay than fight. Among those companies with Android- and Linux-based devices that have capitulated are Amazon, Buffalo, Compal, General Dynamics, HTC, LG Electronics, Samsung, TomTom, Velocity Micro and others.
Barnes & Noble was a holdout, refusing to sign a patent deal with Microsoft, but a coule of months ago, opted to settle and sign with Microsoft. Microsoft invested $300 million in a new joint venture with B&N as part of that settlement.