Chatter can be used as a company intranet or employee directory. Each employee has a profile page with photo and work-related information that explains what the employee’s role is within the company, who the employee reports to, where the employee is located and how to contact the employee. Employees can “follow” both people and documents to collaborate on sales opportunities, service cases, campaigns, projects and tasks. Like Facebook and LinkedIn, Chatter allows users to manage their feeds and control how notifications are received.
Developers can incorporate Chatter features and capabilities to applications built on the Force.com platform. Salesforce offers Chatter in desktop and mobile versions.
This video from Arkadin demonstrates how employees can use Chatter.