MS has said the same thing about Linux to try and dissuade adoption and usage of Linux instead of their systems. Nothing ever became of that.
This is an entirely different situation where Apple could go after handset makers who happen to use the next windows mobile. MS has stepped up and basically told Apple that if they go after MSs partners be prepared for a fight. I know everyone here loves Apple, but do you really think they are going to win in an all out patent war that equates to them versus every other tech company? Highly unlikely. Plus the money and years of litigation would do nothing but bring everyone down. This is why I keep saying that when a large company (I'm not talking about the little guy who gets his one invention stolen) goes on the offensive with their patents they are doing it out of weakness in their products. No matter the outcome it's messy and involves risk for all parties involved.