eCommerce Watch: Hunting the nice holiday price

So we’ve all established that online shopping is a good way to save on gas and avoid the mall, but this just in news suggests that this year a bigger slice of the online transactional pie is going to comparative shopping search engines, those referral banks that allow consumers to compare distributors and prices.
From Nielsen/NetRatings: Traffic rose 61 percent at online comparison shopping sites in the week ending November 27 compared to the week ending October 30. Regular online retailers saw a 35 percent rise in traffic during the same period. Comparison shopping sites, including Shopping.com, BizRate.com and Shopzilla, accounted for 0.3 percent of all Internet traffic -– a 24 percent increase over the same period last year according to Hitwise. (data via Kelsey and zdnet.)
Susan sez: Common belief is that consumers typically use these engines to find fair prices from companies they find reliable–I wonder a) if what is being purchased via these engines is the same as last year, or different? b) how many of the users driving the metrics surge are new users of these services?