Microsoft Exchange Server 2013 is Now Available - Microsoft Server and Tools Blog - Site Home - TechNet Blogs:
http://blogs.technet.com/b/serverandtools/archive/2012/11/02/microsoft-exchange-server-2013-is-available.aspx
If you have software assurance currently active with SBS 2011, you will now see that you have access to Exchange 2013 up in your VLSC site.
Sorting Through BDR Options
Magazine Archive: ChannelPro SMB, May 2013
Transform Your Service Management into an Easy-to-Use and Enjoyable Process