The minor variations are a matter of not infringing on Hasbro's trademark or their copyrighted board (oh yes). And when it comes to trademark usage (unlike copyright or patents), quickly bringing these matters to the courts is proof of the trademark's legitimacy, so yes, there will be a C&D.
At least it's refreshing that there's not a complete sense of naïveté about it like Tris or Scrabulous had. The PR will only raise their profile and they have little to lose.
Man, who knew the Node Knockout would be this, I want to say, historic?! I've seen such great entries and am really impressed with the creativity and skills on display.