SIGGRAPH's Emerging Technologies exhibition changes from year to year, but one thing is pretty constant: its mission to immerse people in a future digital world where technology enables, enlightens and entertains.
In fact, "immerse" might not be a bad word this year. The first three exhibits I saw all had to do with water. Tantalus is a water fountain where the fountain itself is one half of a capacitor; the other half is the person (or people) standing near. The capacitance drives the pumps, which allows you to "sculpt" the water flow without touching it. (Although you can do some neat tricks if you flick the water just right.)
If you really must get your hands wet, there's the liquid touchscreen -- a submerged, face-up touchscreen, where you affect the movement of fish-like creatures by changing the reflectance of the water; it's the ripples, not physical contact, that they respond to.
But probably the most fun is a harp with strings made of water. The sensors actually respond to fingers breaking the beam of light in each "string," but the water adds a tactile aspect and provides one of the few opportunities you'll ever get to splash around electronics equipment.