Using Cellphone Signals to Track Traffic

In Finland this technology is operational since quite some time already around big cities.

In the Netherlands you can see how this happens on the following link
http://actueleverkeersinformatie.brabant.nl/

But the question is then : how does the driver use this information. Around Paris (France) , where I live, trafic is very congested most of the time when people commute. I therefor made the following site to access this information on my mobile phone (SonyEricsson P910i) and this works fine.
http://www.toomonline.com/pda/paristrafic/parisidf .htm

Only then I can adapt my route to get home quicker. I have tried several navigation systems but they often show trafic jams without showing in which direction they are at halt.
Also the small sideroads are not used for directing me around the jams. I know the city well and and use a lot of small sideroads. I don't need that navigator's voice to tell me where to go and hit the jam then.
Having a map as shown in this link, in the car is very practical though. In some cases I choose to drive 7 extra miles to reduce my travelling time by one hour.