>> This is a great idea. However, it needs to be more mobile. If I could access this from my PDA/Phone (Blackberry), then I think I would use it every day.

[www.trapster.com] does exactly this. You push a button when you see a trap, others' phones beep as they approach it. Works on Windows Mobile, BlackBerry, most smartphones, and any phone that has Where.com. Nokia/Symbian version soon. It supports either GPS or WiFi location via Skyhook. If you don't want to run the program on your phone you can also just report traps (via Jott) by calling a toll free number, and get alerts about traps others have reported via SMD. It has a confidence algorithm that learns credibility of traps, and credibility of users over time. Even though you can add, say, red light camera or usual speed trap locations to a map on Trapster, it's not intended to be yet another Google mashups-meets-speedtrap.org. It's a real-time peer-to-peer speed trap sharing system for mobile phones and other devices. And it is patented.