The latest and greatest version of Commerce Server has been released to manufacturing (RTM) and is planned to be generally available in price lists from August 1st 2006.
The 2007 version of Commerce Server especially makes "Connected Commerce" scenarios very easy to achieve thru its webservices interfaces to all subsystems and BizTalk Server Adapters. Synchronizing your Catalog data from SAP to your e-commerce solution has become a matter of configuring.
for more information, documentation and an evaluation edition of Commerce Server 2007 check out: http://www.microsoft.com/commerceserver
CommerceServer 2007 will also be presented at the WebSummit 2006 in Zurich -- for details see: http://blogs.technet.com/chitpro/archive/2006/06/23/LAST_CALL_for_WebSummit_2006_on_Tue_27th_June_2006_at_WTC_Zurich.aspx