Google does the same thing, which annoys me to no end. I'm not sure when they started, within the past few years. They don't even return a Location header, so the links don't work with things like wget or curl.

A link to google.com from the google seearch results is really:

hxxp://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CB0QFjAA&url=http%3A%2F%2Fwww.google.com%2F&ei=LPrOU6a6NYS2yASDzIGADw&usg=AFQjCNG5-9Jej-ukVeakTgwonqt2narbYg&bvm=bv.71667212,d.aWw