Good question. I clicked on that link and this is what it says:
FirstClass is a feature-rich, platform-independent, and cost-effective communications and collaboration software solution that enables learning organizations, including schools, school districts, businesses, and non-profits, to create collaborative online communities that securely connect people and resources via any Internet-accessible device.
FirstClass delivers a broad range of capabilities including e-mail, instant messaging, calendars, contact management, collaboration, document sharing, file storage, web publishing, blogging, podcasting, and voice and fax messaging. Thousands of organizations and millions of users around the world are currently connecting via online communities powered by FirstClass