New Policy For Bulk App Publishing On Marketplace
"In recent weeks a handful of companies have individually published hundreds of apps in a matter of a few days. We call this bulk publishing. While these apps meet our certification requirements and give consumers a wider selection of content, we're also finding that publishing them in bulk degrades our customers' experience. By publishing hundreds of apps in a short amount of time, the popular "New" Marketplace list category fills quickly, pushing the other new apps out and reducing the diversity of the shopping experience."
An interesting article on the Windows Phone Developer Blog goes into quite a bit of detail about the rationale for Microsoft's decision to establish a bulk publishing policy. In a nutshell, the new policy limits the number of apps the Marketplace will publish at one time from a particular developer. They are setting the limit to 20 new apps per day, although a developer can submit more than that for certification at any particular time. The new policy is intended to help Microsoft retain a balance of choice and customer experience by enabling customers to see a broader and more representative assortment of new apps from the developer community when they see "New" apps every day. The Read link has additional information about the new policy.