Mobile shopping is now mainstream, according to a recent study from InMobi. The survey asked 15,000 international mobile users about their shopping frequency, and it seems Americans are adopting mobile commerce at impressive rates.

The survey, relayed by Mobile Commerce Daily, reveals that 74 million Americans currently shop using their mobile phones. More than one-third of consumers who already use the mobile internet say they are comfortable shopping with their mobile devices, while just 16 percent prefer shopping from their PCs or laptops.

The research firm predicts that U.S. mobile shopping sales will reach $9 billion in 2011, demonstrating significant year-over-year growth. In 2010, mobile commerce hit $2.4 billion.

The research firm's prediction is supported by recent stats on mobile commerce released by Google. As Brafton reported, Google concludes that smartphones have become the “ultimate shopping companion,” and 35 percent of consumers have made purchases directly from their mobile devices.

Additionally, Google found that the majority of smartphone owners use the mobile internet to find nearby retailers, and 77 percent regularly use search engines. With this in mind, local SEO may be a good way to reach mobile audiences.