comScore put out some new data on U.S. retail ecommerce spending for the third quarter of 2012. It was up 15% from the same quarter in 2011.

Online retail spending reached $41.9 billion for the quarter, and the fourth quarter is where we should see the real spending. It’s the twelfth consecutive quarter, by the way, that comScore has shown positive year-over-year growth. It’s the eighth consecutive quarter of double digit growth.

“The Q3 growth rate of 15 percent growth remained in line with the prior quarter and provided confirmation of the strength in the e-commerce sector, despite a few negative headwinds in the macroeconomic environment during the quarter,” said comScore chairman Gian Fulgoni. “Such performance offers some optimism as we approach the holiday season, especially given recent improvements in consumer sentiment.”

“With the housing market beginning to show signs of recovery in addition to increasing – if still underwhelming – job growth, there appears to be strong enough footing to support a very healthy online holiday shopping season,” Fulgoni notes.

comScore found the top-performing product categories to be Digital Content & Subscriptions, Consumer Electronics, Event Tickets, Apparel & Accessories, and Computer Software. Each of these grew by at least 16% compared to the year ago quarter.

The firm also found that 37% of U.S. consumers say they have engaged in “showrooming” behavior, where they use a smartphone while in a retail store. Google recently shared some interesting stats about this trend as well.

“The survey also shows that despite a slow-moving economic recovery there has been marked improvement in consumer sentiment in the past quarter, although many consumers still remain challenged by economic conditions,” says comScore. “48 percent of U.S. consumers now rate the economy as ‘poor’ an 8-percentage point improvement vs. the prior quarter and the most pronounced improvement since early 2009 (following the worst of the financial crisis).”