I guess I'll respond to this since I am a battery scientist (well research assistant, close enough) and handle lithium almost daily. The safety of these will probably greatly depend on whether the electrolyte they use is flammable. Lithium by itself isn't going to cause much of a fire, it would mostly react with nitrogen in the air in a completely unexciting manner. If the electrolyte is flammable then there could be significant safety issues if the lithium contacts water. The amount of electrolyte in current Lithium-ion cells causes gases to be expelled if it burns and that is what causes explosions.
A couple other things I notice are, they don't specify the voltage of the cells, or the current they can discharge at, they may only be usable in low current applications. I also know there are regulations about how much metallic lithium you are allowed to bring onto a plane, which would probably limit their use in most devices if they are viable.