U.S. mobile commerce sales will grow 100% this year to $2.4 billion from $1.2 billion in 2009, according to ABI Research, an emerging technologies research and consulting firm. That’s following a 203% jump in 2009 from $396 million in 2008, the firm says.

Growth in the U.S. in 2010 will be fueled by two factors. First, a rapidly increasing amount of consumers with smartphones or other mobile Internet-capable phones. And second, increased competition between retailers triggered by mobile online shopping, says ABI senior analyst Mark Beccue. Consumers leveraged mobile online shopping in 2009 to shop smarter. For instance, consumers shopped physical stores but used mobile online shopping to comparison shop and many times make an immediate purchase from a competitor. Mobile commerce sites will become table-stakes for most retailers in 2010.

By 2015, shoppers worldwide will spend $119 billion on goods and services purchased via mobile phones, representing about 8% of total e-commerce sales, ABI Research predicts.

While the U.S. surpassed the $1 billion mark last year, Japan dwarfed the U.S. at $10 billion, ABI says. M-commerce is growing solidly in Europe, too, and is expected to outpace the U.S. by the end of 2010, the firm adds.

Mobile online shopping is reaching critical mass, Beccue says. In the United States, mobile online shopping rose from $396 million in 2008 to $1.2 billion in 2009. While definitions of mass market adoption’ vary, a 203% increase in one year indicates significant consumer interest.