In US smartphones: Android, Apple, RIM. Together they make up 90% of the market.In demographics, smartphone use peaks among users age 25-34 at 62%, then falls off among the older and younger, reaching 18% among users 65+. Overall penetration for US smartphones is 43%. 
via The Verge - All Posts by Tim Barribeau on 11/3/11
Nielsen's most recent quarterly survey of mobile user shows that while only 43 percent of cellphone users have a smartphone, that number grows to more than half for those 18 to 44. In the "old enough to earn money but young enough to want all the shiny things" age bracket of 25 to 34, that number is as high as 62 percent, where it was only 41 percent a year ago. The 18-to-25 and 35-to-44 demographics are both near 54 percent, but everyone else sits significantly below that, especially those older than 65. All in all it's an upwards trend, and will doubtless only get higher.
The survey also looked at OS share in the smartphone market, and Android is still on top there with 43 percent of users, Apple with 28 percent, and RIM with 18...