On February 16, 2010, Apple has been granted US Patent #7,663,607 titled “Multipoint touchscreen”:
A touch panel having a transparent capacitive sensing medium configured to detect multiple touches or near touches that occur at the same time and at distinct locations in the plane of the touch panel and to produce distinct signals representative of the location of the touches on the plane of the touch panel for each of the multiple touches is disclosed.
The patent application was filed on May 6, 2004. I haven’t read the entire patent (it is fairly long) but it seems to cover broadly displays and systems based on capacitive multitouch technology. It will be interesting to see how others will be able to work around this patent; I think it will be difficult. Source: USPTO via Patently Apple, iLounge, Engadget