At what temperature will the fats on meat render? I am expectantly awaiting the arrival of a sous vide circulator. I saw a clip where someone cooked a duck breast sous vide, finishing it off in a frying pan to crisp the skin. That simply makes no sense to me; as I would have thought that the (rather thick) layer of fat between the skin and the meat would remain, and make the breast nigh on inedible.

Extrapolating from that, I got to think about what temperatures are needed to render fat in genereal.
According to Amazing Ribs:


  130-140°F - Fats begin to melt and render (liquefy). This is a slow
  process and can take hours.


Note:  this is 55-60 C.

The speed of the process will increase with temperature.