Beyond their original plan, Nokia will apparently not be launching their Ovi Store in the U.S. with a carrier billing model. Social aspect of the Ovi store would be the biggest differentiator.

According to IntoMobile:

Nokia plans on integrating new options as quickly as possible, especially for the U.S., where their market share is still negligible. Still, this is a downer for those who were really looking forward to all of the bells and whistles, but the biggest differentiator will be the social aspect of the Ovi Store. It will keep an eye on what you and your friends are downloading, as well as where you are and make pertinent suggestions.