The salt will be sprinkled onto a bowl or peanuts... 
for the on-board elephant that anchors the ultra light Obamamobile firmly on the road. It is for the children and poor folk, don't ya know!
Some additional info here:
http://news.nationalgeographic.com/news/2007/09/070913-burning-water.html
I can’t find much in the way of specifics. Not that I expect it to violate the laws of thermodynamics, but it would be a neat way to generate hydrogen for energy storage - maybe use nukes to generate hydrogen to power pollution-less cars.
One question I have...
If the process breaks up the water into H and O and then “burns” them back into water...what happens to the salt in the saltwater?
That is a good question. I don't believe Sodium Chloride (NaCl) burns. But, I think Sodium does vaporize before 1,000 F (and they said the flame was at 1500 F), and Chlorine is a gas in its natural state. So, perhaps the RF waves break the molecular bonds of NaCL, which causes the Sodium to vaporize, and the Chlorine to escape as a gas - which of course would be toxic - maybe the Chlorine burns as well.
This is why I went to law school, and not MIT.
Most of the salt just stays behind. A small amount would come out as bubbles popped and go into the flame, turning it a nice yellow. I imagine it would just drift into the air and fall out as fine salt dust.
Don’t get to invested in this. It was done as a fun well done hoax and is not real.
What happens to the salt?
You find out when you follow the links to the story of the UC Santa Cruz researcher. The salt ‘stays behind’, e.g., in the original container. The products of combustion of hydrogen and oxygen outside the container is heat and ... pure water. So the process desalinizes the water. And since no carbon is released in the process, well, no carbon imprint.
The salt will be sprinkled onto a bowl or peanuts... for the on-board elephant that anchors the ultra light Obamamobile firmly on the road. It is for the children and poor folk, don't ya know!