Don't have a missing iPhone, but want another Twitter-aided tool that can save you from life's annoyances? Check out Commuter Feed, a network of Twitter users tying to help each other avoid traffic backups and accidents faster than some official city transportations systems are able to update.
The system works by having users follow a Twitter bot that in turn follows their direct messages and sorts through the ones including an IATA airport code and incident information. This code designates which city they're posting for and the rest of your message can simply describe what's wrong. This will instantly go up into a publicly accessible feed that others can subscribe to and check before they head out the door, or from their mobile phones while out and about.
It's worth noting that Google, Yahoo, and Microsoft all have traffic overlays of their own. Many come complete with updated information about exactly what's happened, and in some cases estimations on when each incident will clear up. Your best option is hedge your bets and use both services.