Nielsen's latest statistics on smartphone sales in the U.S. are more than a little eye-catching. They suggest that an important tipping point is on the horizon: The majority of mobile phone users will soon own smartphones, as opposed to feature phones. The majority of cellphone users still own feature phones, Nielsen says, based on its May survey of mobile consumers in the U.S. "The penetration of smartphones is not at the 50 percent mark," said Don Kellogg, senior manager of research and insight for Nielsen. Thirty-eight percent now own smartphones.