The data at left show phones in use (not phones sold) and come from Nielsen Co. The data at right are the projections of Asymco‘s Horace Dediu. If his forecasts are correct — and they’ve been pretty good so far — 50% of the U.S. population will be using smartphones by this time next year, up from less than 30% today and 18% a year ago. He estimates that one in three Americans — or roughly 80 million people — will carry either an Apple AAPL iPhone or a phone running Google’s GOOG Android by 2012.
[Follow Philip Elmer-DeWitt on Twitter @philiped]