Microsoft discontinued the service. This is the message I see when I log into my account:
Thank you for your interest in the product upload beta. Regrettably, we are discontinuing this program.
Merchants located in the United States should consider participating in Bing cashback – an advertising program which combines the power of Bing with a comparison shopping engine to bring consumers some of the best deals on the web.
To get started with Bing cashback contact your account executive or fill out the interest form here: http://advertising.microsoft.com/advertising/cashback
or check out http://www.bing.com/cashback
Product Upload Support Team