Here's another video I found regarding this...
It seems to be a legit idea
JohnB does have a point though, it takes a lot of enery to breakdown water into oxygen and hydrogen, not sure if it's more or less than you'd get from burning it as my highschool chemistry grades weren't great. But with that process you are taking H2O and creating H2 and O2, while this new idea they're talking about is for creating HHO. They're not complete seperating the hydrogen and oxygen, but rearanging the molecules. You still have 2 hydrogens and one oxygen, but with a different arrangement, and apparently the same characteristics of regular hydrogen. It seems as though the energy requirement for this new method might be little enough to actually work, if it can be made efficient enough.
Most of the articles I've read, and videos I've seen, the DIY kits you can make create only moderate amounts of HHO. Meaning there's not enough to run the vehicle from, but as an additive it is able to subsidize your fuel consumption, giving you much better fuel milage. People have said they got anywhere from a 10-12% increase to one I heard about with a grand cherokee getting 56 MPG.
In the video below, this guy says (and seems to have working proof) he created a system that can create enough hydrogen on the fly to actually run without Gasoline.
http://video.google.com/videoplay?docid=-2238805429946487167