Excellent stuff for mornings in the field. Mind you I've only tried the Hot Cocoa which required approximately 10 minutes to heat up all the way while sitting in a cup holder in the truck as I rode to a survey site in the middle of nowhere.
I was surprised that it wasn't scalding hot, instead the cocoa seemed heated up just enough to warm my insides and taste better than microwaved instant hot chocolate. Perfect for when you happen to be away from home because of work.
I wonder if Southwest Airlines would fuss about a can or two in my luggage?
For $2 US it was pretty hot!
Also it seems the heating element uses a limestone + water reaction.
http://store.ontech.com/