What?
Not burned, not electrically heated.  Chemical interaction.  Puff on it, it mixes the chems, and it vaporizes..until used up.
I read it somewhere in some link in the last week.  Might have otherwise commented on it. 
You know, like mixing acids and bases or something.  
For all I know it makes your lungs drop 
through your anus, but you probably get a hell of a cloud before you keel over.