Something about the length of the thing, attached at the back, balancing and then tacking and/or jibing.
UNTIL i saw some pictures of the iFoil... Here is an unlisted video :
There is also FINALLY a decent write-up on the board here:
I will let the article and video speak for themselves.
Suffice it to say - it looks HOT !!
not so sure about those lights :-)
Fin is STILL 70 cm, but as the designer says: