Multi-touch (or multitouch) denotes a set of interaction techniques which allow computer or mobile users to control graphical user interface with more than one finger at either application or system level.Multi-touch consists of a touch screen (screen, overlay, table, wall, etc.) or touchpad, as well as software that recognizes multiple simultaneous touch points, as opposed to the single touchscreen (e.g. computer touchpad, ATM), which recognizes only one touch point.

This effect is achieved through a variety of means, including: heat, finger pressure, high capture rate cameras, infrared light, optic capture, tuned electromagnetic induction, ultrasonic receivers, transducer microphones, laser rangefinders,
and shadow capture.

CeWiDus has worked on multi-touch support on OMAP 3530 (Windows CE 6.0 R3)
OMAP 35x TI processor interfaced Touch Screen Controller
The TSC2046 is a next-generation version to the ADS7846 4-wire touch screen controller which supports a low-voltage I/O interface from 1.5V to 5.25V

Applications
PERSONAL DIGITAL ASSISTANTS
PORTABLE INSTRUMENTS
POINT-OF-SALE TERMINALS
PAGERS
TOUCH SCREEN MONITORS
CELLULAR PHONES

TI Davinci DM644x processor interfaced Touch Screen Controller
TSC2111
12-bit 4-wire resistive touch screen converter
Touch Screen Processor With Fully Automated Modes of Operation
Built-In Buffer for Touch Screen Data
Interfaces to host controller through a standard SPI serial interface

Applications
Personal Digital Assistants
Smart Cellular Phones

Touch Screen Device drivers supported on Windows CE 4.2, 5.0, 6.0, uCLinux, Micro ITRON, OS independent drivers
USB device interface support for device side and PC side
PC side software and application development

Device driver support for
Analog resistive touch panels
Digital resistive touch panels
Multi-touch surface with capacitive sensor array
Impressive demos and contents for showcasing touch screen controllers and panels
Production Quality software with applications support