Though Apple usually prefers two sources for its components—better to foster competition among the vassals and keep supply chains nice and smooth—BusinessWeek says "it's an open secret" that German touchscreen maker Balda is the only squire worthy enough to build the Apple iPhone screen.
Balda now makes glass-surfaced screens that are far more sensitive, thinner, and harder to scratch or smudge than the plastic displays that now dominate. They offer sharper resolution, and unlike conventional touch screens—which get confused by more than one finger at a time—Balda's displays can sense several human digits simultaneously.
Balda's got some secret Chinese technology that gives it the two-fingered advantage, good for Apple's purposes. Even though the Mac daddy was well known for its stubborn use of a one-button mouse, it did usher in the age of two-fingered track-padding. It will likely do the same for phones, with iPhone's thumb-and-forefinger "multitouch" for zooming in on photos. Besides being sensitive enough for two distinct finger touches, Balda's glass screens are reported to be sharper, thinner and more resistant to scratches and smears—another subject Apple has learned plenty about in recent years.
And there's the question of whether or not Balda's screen is exclusive to Apple.
Balda: The iPhone's German Accent [BusinessWeek]