I saw this today on Boing Boing, linked via a website called doobybrain. It's called a beard cap, and it's brought to you by a place in Brooklyn called Scandinavian Grace.
The beard cap is made of wool, comes in different colors and lengths, and makes you look like (depending on the length or color you choose) a psychology professor, a Viking, a gnome, or Fidel Castro. I would happily wear one of these as I walked my dog or shoveled my driveway during the cold-weather months.
You can get the nifty head-coverings here, although when I tried I was told that their bandwidth was exceeded.
UPDATE: Perhaps it's just as well. I see that these hats cost a whopping $135.00. Fuggit...I'll just grow my own beard instead.