Had someone with a Nexus that already had JellyBean on it and he gave me a demonstration of "Google Now". Never was that interested in the whole Siri thing but I have to say I was damned impressed. And now I know how tall Mt. Everest is too!
Nexus 5 32GB
HTC Droid DNA
LG G2, Samsung Galaxy S4, Samsung Galaxy Note II, Samsung Galaxy SIII, HTC One S, Toshiba Thrive Tablet, Samsung Galaxy Note, Samsung Galaxy SII, LG G2X, MyTouch 4G Slide, iPhone 4s, MyTouch 4G, iPhone 3GS, Some Blackberries, HTC Diamond Touch, HTC Mogul, HTC PC6700, handful of Nokias... all the way back to the original Motorola MicroTAC in 1994.