Promo video of it here: http://vimeo.com/65461286
Their home page, with demos: http://www.gooengine.com/
Feel free to request an invite, but I have been accepted and will gladly share the tools available to members with anyone. I’m not sure if they’re planning on charging some day, but since it is still not version 1.0, everything is free.
Check out Art Gallery (Especially the part where you can keep zooming in on the scene recursively), ocean or turbulent ocean, and Goo 4 Dead (just a video unfortunately).