These guys have basically taken the DNA that glows when you shine UV light on it, and put it into a fog. Such that if you are at the scene when the fog goes off, you'll glow too.
This is the beginning of a trend that I'm not sure is going to turn out well. For example, everyone knows that your piss smells after you eat asparagus. Now lets say you put an odorless aerosol in the 'target' area which disperses a variant on the asparagus enzyme. Now back at the office you've got a detector in the urinals and free soda. Is this surveillance? Is this a violation of your 5th amendment rights? (spot tests of urine have been tested in court and upheld)
Note that I'm one step past folks who completely change all their clothes and wash their hair to avoid detection. That will be the first step of course.
We've become so facile at collecting DNA and analyzing it at crime scenes, seems like this is a logical next step. Give the crime scene some DNA that it can put on the criminals, you would be hard pressed to contest a search for some "other" DNA on your clothes I expect.