NASA’s New 10-Engine Drone Is Half Chopper, Half Plane
wired.com
wired.com
That one doesn't do VTOL but there are apparently nontrivial efficiency gains from that configuration even without tilting the wings. If you could get enough efficiency gains from the reduced wing loading to offset the weight of the wing tilting apparatus you could effectively get VTOL 'for free' (maybe, I don't know jack about aerodynamics).
http://helicopters.axlegeeks.com/compare/18-24/Sikorsky-CH-5...
As I understand it the main drawback of the V-22 is the drag effect of the "larger" blades in airplane mode. So I assume that NASA is testing tilt-rotor aircraft with more engines with smaller blades in hopes of increasing the range and speed over current tilt-rotor aircraft.