Via Shane's Place: Rosum TV-GPS - the website has a fairly good description of how they use TV signals for LBS, plus a pretty diagram, too. =)
Is it a good thing that there are so many ways of positioning, or is it just confusing? If they can't all work together, then will one of them will have to win out over the others in the end? Kind of like how there's GSM and CDMA... In the end though, the more people who work at LBS applications, the better!