according to Microsoft, its not true
http://www.gamespot.com/news/2005/06/30/news_6128428.html
http://www.gamespot.com/news/2005/06/30/news_6128428.html
"To be clear, Xbox will continue to be manufactured exclusively by Microsoft," said a rep for the company. "There's certainly a potential for other hardware companies to manufacture Xbox some day in the future, but that is not something we're focused on right now."