The Gourmet Whip was initially intended for making whipped cream (like chantilly) by injecting a neutral gas. But now it is used for many other foams, in different flavours, savoury or sweet, cold or hot.
It was the Catalan chef Ferran Adria who started to use a Gourmet Whip to make his famous "espumas" (Catalan word for foams), sometimes hot, in surprising flavours.
If you intend to buy:
Don't get a "chantilly cream whip" which will be too limited. See the best addresses page for more informations.