On Monday, Nielsen Mobile released first quarter 2008 smartphone statistics for the U.S.  Among the findings:

Smartphone users are predominantly male (59%) and most are between the ages of 25 and 34 (29%) or 35 and 44 (24.5%). 

A third of smartphone users (35.1%) have an annual household income of more than $100,000. 

More than half (52%) keep their phones for personal use, while another 23% say their company foots the bill.

View the Full Nielsen Media Alert: 6-30-08-smartphone-blast.