EOS is based on CRE Loaded B2B. B2B is definitely in its future. It is suitable for use by retailers also, because of our reimplementation of the price break structure.
Multiple vendor or warehouse shipping is planned. We do not plan to reuse the osCommerce contribution as CRE did, but to update / modify the core shipping system to handle freight and shipping more effectively.
Our development team is currently myself and Tom O'Neill (zip1). The focus on code development has largely on code cleanup and organization with reimplementation of some key systems. Code consolidation has been a high priority, with several content management systems already collapsed into what used to be the page manager. Quite a bit of operational streamlining in other words.
We've also put some effort into creating a community based code development infrastructure. It is our belief that having store owners, customers, hosts and support vendors involved from the beginning of the development cycle will result in a cart which is more powerful and usable.
Open design is supported by the use of our Wiki to build design documents in which the community can participate. Open Development is possible through our subversion repository setup.
We have some other features to implement in order to support the process - including the ability to vote on posts so that we can get community feedback that is quantifiable for use in development planning.
There is no specific plan for a "vendor mall" type distribution. That said, we do have a commitment to being branch friendly and to continuing to collaborate with branch focused teams in maintaining a common core in true Open Source fashion.