Why mobile companies should get into maps and traffic

Why mobile companies should do real time traffic analysis ? sounds wierd but the more you think of it .. why dont they do it already. I was thinking about real time traffic analysis and an interesting idea cropped up.
What network enabled device is present in almost every car on the street radios and cell phones. We use radio waves (XM radio ) today to get real time traffic data. The XM transmitter gets this data from all sorts of sources. But the draw back is these sources are only available on the larger highways and mostly in north america and europe. The rest of the world doesnt have this technology, but what most of the remaining world has is cell phones. Cell networks cover almost every corner of the world (well all the important corners anyway). They have the ability to pinpoint any cell phone suscriber (most subscribers have this ability in most places .. think they use triangulation) and they have access to maps. Almost every car / bike has a cell phone these days.
Combine the fact that cell phone providers have access to maps, ability to located subscribers we get real time traffic reports for almost every road in the world :). There will always be minor (?) technical difficulties in getting live traffic reports on and from cell phones, but nothing that cant be solved with a little bits of traffic prediction technologies and data aggregation.

Want to share an idea.. this is my g m @ i l :b l o g t a m m a