The Register (a UK computer and tech news site) reports that an automatic number plate recognition (ANPR) system will go live in April of this year (2006). The system will be used to log vehicle movements across the whole of the UK in order to apprehend suspected criminals as well as identify and track stolen, unregistered, and untaxed vehicles. The system will have cameras every 400 yards (365 meters) along motorways ('interstates', in US English) and will capture images 24 hours per day, 7 days per week. Given the traffic on UK motorways, that means processing about 50 million number plates (a.k.a. license tags) a day. A mobile ANPR unit is shown in the photo here.
Hat tip Technovelgy.