UltraHaptics is a system for creating haptic feedback in mid-air. Waves of ultrasound displace the air, creating a pressure difference. By causing many waves to arrive at the same place simultaneously, a noticeable pressure difference is created at that point. With this method, we are able to create multiple, concurrent points of haptic feedback in mid-air.

They have more interesting projects, for instance:

http://big.cs.bris.ac.uk/projects/

(it`s not news, but dont know where else to post)