Although Microsoft and Apple have initiative in touch interface, there are many people who are working on next touch interface.
N-trig DuoSense provides dual mode pen and multi-touch sensing with the combination of capacitive and electrostatic sensing techniques.
Microsoft ThinSight utilizes infrared LED and sensor to detect multi-touch. Unlike MS Surface, its sensor system is tightly coupled with the backpanel of the LCD display.
Microsoft seems to be passionated by touch interface. With LucidTouch, you can control a device by touching its rear side. Unlike other rear side touch, you can still see your fingers although they are moving on the backside of the device.
Mitsubishi should be appreciated as a pioneer of surface computing. DiamondTouch is a table top interface system supporting multi-user collaboration.
Philips have been joined table top interaction with Entertaible, which takes use of infrared sensing technology.
Sony's SmartSkin is a multi-touch table top interface. The interesting point is that its sensing technology is very similar with that used in iPhone - mutual capacitive sensing.
Touch KO, now acquired by Wacom showed off touchless touch. The so-called Spatial Capacitive Touch lets users control comptuer interfaces by hand movement from up to 6 inches away.
Stantum Multi Touch utilizes resistive touch sensing while most other competitors prefer capacitive or vision-based approaches.
Tactiva Tactapad reconstructs hand motion by using a pressure sensor and camera.
Touch interface is not just for flat, rectangular display.