Good feature, minimal product. Go forward or move on to something else?
danvoell: +1 on the value is in the data comment. Pick one platform and go all out. You should be able to partner with quite a few existing products. 
+1 on the time of day comment. It's most definitely a different business to the one you are proposing but a valid thought. There is value to a system which can show how many people are in line at a given establishment at a given time. Both to the consumer and to the company. Can you coordinate how many cell phone signals are in an establishment similar to the companies that track cell phones on the freeway for congestion monitoring?