What are some alternatives?
Workplace by Facebook - Connect everyone in your company and turn ideas into action.
Bitrix24 - Bitrix24 is a free (for small businesses) social enterprise platform. It is a united work space which handles the many aspects of daily operations and tasks. Create your own social intranet in minutes!
Salesforce Chatter - Salesforce Chatter provides a suite of collaboration features to any application built on Force.com.
Zoho Connect - Zoho Connect is a team collaboration software that helps teams ideate, discuss, and work together, from any place, on any device.
Yammer - Yammer is a leading enterprise social network used by more than 200,000 companies worldwide, including 85% of the Fortune 500, to get work done smarter and faster. Sign Up Today.
xcomms - XComms provides an internal employee communication tools that allow send out desktop alerts through various flexible messaging channels, reach all employees directly with full desktop targeting, scheduling and real time acknowledgement reporting.