I have heard of it. It's mentioned on US forums a lot and many people who have problems with cats going outside the litter tray seem to have had success with getting them to use the tray by using the cat attract (not people I know personally, just posts on forums). You can get the actual litter or an additive to add to normal litter. Not sure what is in it, but it is supposed to attract cats to the litter and prove irresistible!