The NYC Food Truck Finder is used to find food trucks in realtime on the streets of New York. Food trucks are put on the map by automatic aggregation of social media feeds, published food truck schedules, and from dedicated GPS devices in trucks. Not only does this website publish food truck locations, it also notifies you via regional twitter accounts and via browser notifications from Chrome.
I am currently working on some new ways to accomplish notifications, but these are your best bets:
The Food Truck Finder Notifier chrome extension is in the Chrome store. This puts an icon on your Chrome toolbar that indicates how many food trucks are nearby.
I have regional twitter accounts which retweets any truck that mentions a specific location, and sends out a daily lunch-time summary tweet. Below is a map that lists them all.
This is not something I can currently do effectively, so your best bet is to use to peruse the selection of trucks on this website and contact them individually.