According to data from NPD Group the iPhone lost its position of the best selling smartphone in the U.S. during the first quarter of 2009 to the BlackBerry Curve.
According to NPD the top five bestselling smartphones in the U.S. during Q109 were:
1. BlackBerry Curve (all 8300 models)
2. Apple iPhone
3. BlackBerry Storm
4. BlackBerry Pearl
5. T-Mobile G1