The iPhone is the second biggest-selling smartphone in the US, confirms new research from Synergy Research Group.

The Synergy Q2 2008 Mobile Handset Market Share report confirms the US smartphone market posted strong double-digit growth, with the iPhone continuing to break records, shipping over a million units in

three consecutive quarters. 

"Even with Q2 shipments dropping in anticipation of the new 3G iPhone, Apple retained the second place spot for the first half of the year with Motorola a close third," the researchers said.

Motorola is currently the number one US mobile vendor with 25 per cent of the overall market, but it's facing challenges taking a bite of the growing smartphone sector, researchers explained. "In Q2 2008, Motorola was the only vendor in our study posting double-digit drops for both sequential and annual growth."

In the first half of 2008, the US smartphone market represented 12.2 per cent of total mobile handsets shipped, the sector represented just 10 per cent of overall mobile sales in the first half of 2007.

While Apple's share of the smartphone market fell 64.2 per cent in the weeks before launch of the iPhone 3G, the company still saw growth of 125.6 per cent year-on-year in terms of marketshare, the analysts said. RIM grew 92.1 per cent, while Samsung and Sony Ericsson experienced growth in the low 30's. Motorola's overall smartphone market share shrank 18.2 per cent, year-on-year, while Nokia saw its US smartphone share slide 24.5 per cent.

Right now it's RIM's game to lose, the researchers said: "Despite the rock star status of the Apple iPhone, the Blackberry (RIM) dominates the US market with a market share of 46 per cent (first half of 2008) versus Apple's 15 percent," said Aaron Vance, Senior Analyst, Synergy Research Group. "But with iPhone's continued strong success, which only took Apple a year to achieve a number 2 ranking, it may be sooner than later that Apple is challenging the Blackberry, a notion that would have seemed impossible to many a year or two ago."