It's part of a quick-shifter kit I had installed.
http://www.flatshifter.com/flat-shifter-pro/. My bike is set up to be able to do clutchless shifts. Can still shift normally as well. When I shift w/o using the clutch the engine gets cut off for a split second and allows the "magic" to happen. Not really sure about the specifics. In my limited riding so far, the upshift works really well as long as it's revving above 5k. Have not tried any aggressive clutchless downshifting.