truXmap claims to be the "world's first and only up-to-the-tweet food truck tracker". The site uses Google Maps to show the location of food trucks in Los Angeles.
Using the map it is possible to browse the locations of food trucks, opening times, menus, directions, live traffic, Twitter feeds and Yelp! reviews.
The site claims to be 99.9% effective. I think there may be some truth in that. The reason I say that is because one of the food truck companies displayed on the map, Calbi actually has live tracking Google Maps for each of its trucks. The live real-time tracking on the Calbi site seems to co-relate with the locations of the trucks as shown on truXmap.
Calbi Food Truck Locator