Commerce Server 2009 should be a good solution for anyone on looking for an Online store and an easy to use CMS.
With its sharepoint functionality built in, it could suit large retailers with multiple different stores with the ability to create a new sub site from the administration section, customize the UI, add new products and you've got a new online store setup which is a sub site of your complete collection.
The new out-of-the-box shopping site leverages SharePoint Commerce
Services, which provides a gallery of ASP.NET 3.5 Web Parts and
controls, a comprehensive e-commerce shopping feature-set, and
technology integration between Commerce Server and SharePoint
technologies. The Multi-Channel Commerce Foundation provides a new
unified, extensible run-time programming model for Commerce Server,
including new run-time e-commerce capabilities.
http://www.microsoft.com/commerceserver/default.mspx