It's a chat platform and you can sign up for free. One can upload files and images, and it can tie in to other platforms (though I think these are all workplace oriented).
Sounds neat, but if it's a work thing that's probably why I haven't heard of it. Would make no difference to my job. :)

Actually the thing that caught my attention was IRC use in 2004. If someone had quizzed me, I would have assumed its peak use was at least 3 years earlier!
Yeah, barely heard of that either. (Not that I care. *g*)