The Sony Ericsson Xperia X10 suffered from a lack of multi-touch, a flaw that saw it often derided as a true smartphone contender with its lack of gesture support. In a complete one-eighty turn, the Sony Ericsson Xperia Arc will support as many points of multi-touch interaction as you can throw at it thanks to its Cypress TrueTouch All-Point digitizer.
The Cypress product page cites up to “32 X/Y sensor inputs,” which the astute reader will note is not actually unlimited. Compared to the number of fingers on the average human being, even if you get the toes involved you’d still have room for 12 more points of reference. For all intents and purposes we’ll call that unlimited in this instance.