There was a thread about them sometime back:
http://forums.equipped.org/ubbthreads.php?ubb=showflat&Number=256698

I recieved one as a gift last year. The heat of the stove charges a battery that runs a fan to provide draft for the stove. When it gets hot enough it will also charge an iphone. It actually seems to work pretty well, both in terms of heat output and charging an iphone. (I haven't tried to use it to charge my ipad.)

The main drawback is that it is rather heavy if one is backpacking. For that reason I haven't used it much. It would probably be OK as long as you don't need to carry it in a pack. I'll be doing a bit of car camping in the near future, and I may take the Biolite along and see if it works to charge my ipad.