Brian Smith was the first that I know of to report that Bing Shopping is now free for merchants to sign up with and list their products.
Brian Smith runs SingleFeed, a shopping search engine merchant feed service, that does what the name promises.
As I mentioned in my Search Engine Land piece, Bing Shopping was fee based and they changed the page to say it was free. There is also a PDF with more details.
As you know, Bing's Cashback program discontinued on July 31st. Bing quietly, I still don't see an announcement, is allowing merchants to submit their products to Bing Shopping for free now. The merchant submission form is over here. Again, I am not sure why they are keeping this so hush hush or if I missed an announcement from them.
They do have a forum dedicated to Bing Shopping Help. Carolyn Miller from Microsoft said in one thread:
Welcome to the Bing Shopping forum!This forum is designed for merchants wishing to collaborate on best practices and ideas for the Bing Shopping program.
Carolyn Miller
adCenter Community Team PM
Forum discussion at Bing Shopping Help.