“The advanced technology takes anti-ghosting to the next level by allowing gamers to press up to 26 keys at once. Because each key is scanned independently by the keyboard hardware, each key press is correctly detected regardless of how many other keys are being pressed at the same time.”
What is more interesting with SideWinder X4 is that Paul Dietz has contributed to developing it. He developed DiamondTouch that is one of the first capacitive multi touch systems and is available through Circle Twelve.
Link: Tech News Daily, “Exclusive: Hands on: SideWinder X4 keyboard review”