Commerce Server 2009 provides some great new features to greatly decrease time-to-market with a pre-built site to get you started. There is support for cross-channel out of the box, with a pre-built mobile channel that can be maintained inside SharePoint. There is also a brand new programming model to make developing against Commerce Server much easier and more efficient than it ever has been. CS09 becomes widely available to purchase on April 1st, 2009, but until then feel free to check out some of the resources below:
MSDN Subscriber Downloads
http://msdn.microsoft.com/en-us/subscriptions/default.aspx
Product Website
http://www.microsoft.com/commerceserver/
Partner Information
https://partner.microsoft.com/US/productssolutions/servers/commerceserver/
Forums on MSDN
http://social.msdn.microsoft.com/Forums/en-US/commserver2009/threads/
Multi-Channel Foundation Samples
http://code.msdn.microsoft.com/CS2K9Samples
Default SharePoint Site Performance Guide
I’m sure you will agree that there are some great advances in the platform, but let me know what your thoughts are in the comments.