Kapil,
Just to clear a few things up. What Furfly and I will be releasing in alpha form within a few days is a straight port of the ACS 3x ecommerce module to work on ACS 4x. It is not a direct descendent of the code that aD started for a ACS 4x redesign of E-commerce. It won't support multiple retailers out of the box or multiple instances of the package. If you are familiar with the 3x version of E-commerce, not much has changed.
I'll be including more details in the release notes.