This topic meshes perfectly with the insights of the past few Monday Outlooks as it will be a popular piece in stores. Not so much considered faux pas, but they definitely aren't a widely accepted piece in the men's world; this fact might be a little different this fall and winter.
Seeing as the move is towards mixing and matching professional and casual, the turtleneck is the perfect addition to a suit or sport coat, creating an elevated sophistication to the look. Yes, its going to look slightly nerdy, but I heard somewhere that smart is in (queue the pictures of NBA post game interviews in their faux glasses). There isn't really much to say on choice of color or fabric, its just like any other sweater you own, but there needs to be a significant emphasis placed on the texture. Anything too plain Jane and you'll look like you're wearing Under Armor, so get something with deep ridges or visible stitch variations that will add some much needed gravitas for the winter.
Check in tomorrow for the next installment of my Friday Faux Pas and next Thursday for another fashion piece that deserves your consideration!