There are some reports about AirSig.

http://spectrum.ieee.org/consumer-electronics/portable-devices/inair-signature-gives-mobile-security-to-the-passwordchallenged

http://www.mobilecommercepress.com/mobile-security-gets-boost-air-signatures/859644/

http://www.mobilesecurityzone.com/topics/mobile-security/articles/361795-airsig-introduces-new-way-enter-password.htm