Facebook’s business product — which it says will replace or augment email, IM and collaboration app — was on display at F8 this week but never shown or even mentioned on the big stage. There was a small booth at Facebook’s annual conference where attendees could see short canned demonstrations of Facebook at Work, but the product was generally an afterthought amidst the news surrounding bots on Messenger, live video, artificial intelligence, virtual reality and other developments to Facebook’s core properties and initiatives.