Basically what the app does is using GRP, it will pre-empt you of approaching fixed redlight cameras or speed cameras....and when you are very near (you can set the distance), you can set an alarm to sound off.
I just got the app...2.99 USD...and tried it...well not too bad....managed to sound off before I hit the redlight cameras and also tells me how far am i from the cameras.
Anyone using this or other aps?