ComScore said online retail spending was nearly $34 billion for the first three months of 2010, up 10 percent year-over-year, the first time growth rates reached double-digits since the second quarter of 2008.

ComScore chairman Gian Fulgoni said, "While these spending gains provide reason for optimism, we should note that upper-income households are currently shouldering much of the growth. Should the economy falter in the second half of the year and upper-income consumers return to a savings mode, we could still see growth decelerate. But for the time being, this momentum is encouraging."

Other highlights from the first quarter include:

• Growth in the first quarter was predominantly driven by upper-income consumers, with spending among the $100,000+ household income segment up 14 percent.
• Pureplay (online-only) retailers continued to gain ecommerce spending market share from multichannel retailers.
• Larger online retailers continued to generate higher growth rates than smaller retailers, but the smaller retailers are finally beginning to see positive growth once again.

ComScore is holding a webinar on the state of U.S. online retail and will share survey findings highlighting consumer sentiments regarding the economy on May 27, more information is available on the registration page.