Because a shoes rubber outsole is its heaviest part, companies can save a lot of weight by getting rid of it and using a midsole material thats more abrasion-resistant than normal. Reebok did this first with its 3D Ultralyte racer/trainers, and then a short-lived 180g racing shoe.
Adidas came up with the outrageously-light mesh-soled 131g Mangostin
in summer, and now Nike has produced something in between. Still crazy-light by any normal runners standards, the Air Streak Vapor has thicker cushioning (but less stability because of it) than the Mangostin. It also has a firmer strip of midsole material for better traction and durability than the mesh-soled Mangostin. The reality is that most runners wouldnt be able to go near either shoe for fear of injury. However (and we probably shouldnt tell you this), neither shoe is actually as badly cushioned as youd expect our most biomechanically efficient and resilient tester has comfortably run above 10K in them.