For the last few years, Microsoft has been making vague threats to sue vendors of Linux-based products for infringing on Microsoft's patents. When Microsoft is asked to elaborate on what exactly is being infringed, it suffers a convenient case of amnesia. In any case, while it has bullied a few companies (first Novell over SUSE, now companies like HTC over Android) into paying excessive royalty fees for no reason, it has never made good on its threats to sue anyone, probably because it would be clear as day just how ridiculous Microsoft's infringement claims really are.
It seems like now, as this article (Adam Hwang, Digitimes) points out, Microsoft could possibly make good on this, although it seems like it's just bullying companies into paying royalty fees as opposed to outright suing. It's charging AsusTEK and Acer royalty fees for the very vague "email, multimedia, and other" functions just to make sure they don't sell netbooks or tablets with Android or Chrome OS on them. It would be a shame if these companies submitted to Microsoft's demand, but it'll probably happen considering that the same thing happened to Novell and HTC; then again, consumers are now more aware than ever of alternatives to Microsoft Windows, so I think they may actually seek out and demand Android and Chrome OS devices anyway. Let's see how this turns out.