I don't think there are any.
Many multi-function printers also come with slots for various types of camera media. Thus effectively making them network-atttached disk drives.
If I were managing printers inside the Pentagon, or inside a major defense contractor, I'd be thinking really carefully about this one. And if I were managing IT inside a big company, I'd be doing as the article suggests, starting to talk up my printer vendors on this, to see what story they have, to begin to encourage them to actually get a clue, and to begin to reward those who take this seriously with more business.
But I see no evidence that this is the year that those of us in small, mundane businesses, or those of us at home or in home offices, should worry. I'll be spending about as much time worrying about this as I worry about threat vectors for Lockheed C-5A Galaxy transports.
Besides, even if it was the year for us ordinary folks to worry about this, there ain't a damn thing you can do yet, except that which would be more effort than it was worth, and require specialized expertise that few have.
Printers are certainly potential threat vectors. They are special purpose computers sitting on the network, ill managed and fully equipped. But (1) the potential isn't being realized yet -- crackers haven't mounted widespread attacks using them yet, and (2) nor are the practical protections there yet either -- neither printer nor security vendors have much to sell you here, nor do us Open Software hackers have much for you to download, compile and mess with yourself, that any ordinary person would find useful.