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Right now it is invite only, and aimed at developers. I'm here to beg for an invite! If any of you have accounts and can spare an invite for me, I would be very grateful.
I didn't heard about it, i am discovering it today.
The good news is that I got in! The bad news is that they didn't give me a single invite, so the only person I can communicate with on the platform is the guy who invited me.
Still, this is a very cool collaboration tool, and I think it has the potential to be something absolutely huge.