Case study: The Hub by SAS
SAS launched The Hub, based on Socialcast, in 2011.
In a case study they explain that SAS had a number of requirements, including:
"All communications would have to be maintained behind the firewall (for security reasons) while seamlessly integrating with other internal business systems such as SharePoint."
That is, Socialcast was deployed on premise (unlike Yammer and similar solutions, which offer a cloud-only deployment model).
Socialcast’s Reach extension allowed a two-way integration with their intranet.