I see no reason to believe that’s a single part that anyone sells; more likely it’s a standard rotary encoder, surrounded by a ring of rectangular LEDs, covered by a custom-molded piece of translucent plastic.
Lumex makes some curved LED bargraph arrays that might be a good start for making something similar; see, for example, http://search.digikey.com/scripts/DkSea … 67-1524-ND.