If your interested in seeing how Commerce Server and SharePoint can be integrated, you might want to take a look at the December 2008 CTP of Commerce Server 2009:
The bullet point of interest is:
- Complete out-of-the-box e-commerce shopping site in SharePoint with new search functionality, new shopping features, and what-you-see-is-what-you-get (WYSIWYG) content management and design experiences. This helps to facilitate rapid assembly and maintenance of e-commerce Web sites by business users and creative professionals.
For more information about this upcoming release, the PDC session is a good place to start.