Edit: The much better link to read is probably this: SlateStarCodex on Facesmasks – Much more than you wanted to know.
Link of the day: Professional and Home-Made Face Masks Reduce Exposure to Respiratory Infections among the General Population
There are many good arguments for low-risk people not to buy and hoard face masks to leave them to the ones who need them most. As far as I can tell, however, face masks do work. And in an ideal world, we would probably all be wearing them right now.