Perhaps 2009 is the year of the underdog. The BlackBerry Curve snagged the coveted No. 1 spot in smartphone sales in the first quarter, edging out the iPhone with a “buy one get one free” promotion. The Curve is also available through four cell phone carriers, while the iPhone is still restricted to AT&T. The iPhone might recapture the title now that the Curve’s promotion over, but the highly anticipated Palm Pre, from Sprint, could be the next smartphone heavyweight—the carrier is planning a major marketing campaign.