E2.0 activities evolve to include mixed communities made up of employees and external business partners. There are some camps that continue to call this Enterprise 2.0 and others that want to call it something else (external Collaboration for example).
Social Business pulls it all together to convey any business use of social media or web 2.0 activities and practices. Just like E-Business pulled it all together in the early e-commerce days, I believe Social Business pulls it all together for corporate web 2.0 applications today. #SocBiz is the hashtag.
Very nice summary and definition, why we should call it Social Business.