Treebranch Menu - How To - Please Help

I just witnessed a truly amazing, yet simple menu system here:

If you click “start here” you’ll see what I’m talking about.

I’d like to pull of this treebranch effect with the elements sort of gravitating in relationship to a centerpoint and the mouse location, as well as dynamically positioning themselves in relationship to the last selected item. It seems like these are the two functions in effect here. Can anyone point me in the general direction of how this is done, a tutorial perhaps?

Thanks in advance for any help, this is such a cool effect!