Safer cell phone use while driving??

This article presents an interesting concept, but I am not so sure it would be as effective as they think. The basic idea is that your cell phone will chirp (the same sound as the pedestrian crosswalk warning) when you get within 100 meters of a traffic light.

The idea is that many drivers who are talking on their cell phones don't notice it turn red and hit pedestrians or stopped cars. It is based on GPS, so you don't need any fancy technology, just a GPS enabled phone. It is connected to a database of traffic light locations.

But this means it will chirp even for green lights. So my questions are:
1. Will drivers habituate to the sound and start ignoring it? This could happen either for drivers who pass traffic lights a lot - habituation based on frequency of red and green lights - or when drivers start to ignore chirps because they often warn about green lights - habituation based on proportion of false alarms. The Human Factors research on trust in automation could probably predict what will happen, but focused research is probably needed.

2. Will drivers get annoyed by the chirp and either turn it off or just ignore it for aesthetic reasons? After all, it would have to be salient enough to draw attention away from the conversation for it to work. So the annoyance is virtually guaranteed for a large proportion of the user group.

What do you think?