from 1UP.COM:
Two interesting Xbox-related rumors popped up on the web today. According to popular gizmo website Engadget, the official name for the next generation Xbox, often referred to as Xbox Next, Xbox 2, or Xenon, is actually "Xbox 360." According to Engadget, the name was test-marketed and a source working on the project has confirmed it to them.
http://1up.com/do/newsStory?cId=3138221