Widescale monitoring that is in the works now.
China is looking to use RFIDs to track 13 billion chickens.
Recent RFID pricing is 7.2 cents per tag in orders of 10 million China is issuing RFID identity cards.
This site has discussed RFID technology before
Even without molecular nanotechnology...by applying moore's law to RFIDs. In 20 years, RFIDs are 1000 times more powerful for the same price or 1000 times cheaper.