Some interesting stats from MSN regarding the audience profile of the (and maybe some MSN Live in there as well).
An almost even split between men and women, and a high household income on average.
The one stat that stands out to me is the fact that 75% of the Bing audience is above the age of 25, and 33% are above 55 years old. And incredible number of 'Zoomers' use the MSN search portal, and according to the overall stats, have previously shopped online, so would be willing to do so again.