Here's a look at Facebook's plan to kill unicorn startup Slack - SFGate

Check the full article for screenshots and more details; also see Facebook Is About to Take the Training Wheels off Facebook at Work (Re/code)

"Facebook plans to launch the product for free and will offer premium features that businesses can choose to pay for (no ads, ever). By vying to be the main internal communication tool for businesses, Facebook is strongly challenging other established products like Yammer, owned by Microsoft, or Slack, which is one of the fastest-growing business apps of all time and  now worth an estimated $2.8 billion, having raised $160 million. 
Facebook told Business Insider the company is rolling out the "for work" product to hundreds of more test companies, and that companies that have already signed on, like Heineken and Hootsuite, are "experiencing solid daily engagement rates" and"seeing increased productivity using the Groups and News Feed features.""

Here's a look at Facebook's plan to kill unicorn startup Slack - SFGate