The mark

This is very old news, but a scary new discovery for me - http://news.bbc.co.uk/2/hi/technology/6389581.stm

It seems that RFID tags are now smaller than a grain of dust, measuring 0.4mm x 0.4mm, this means that some one could blow dust over a croud of people and tag them like cattle without even the slightest knowledge, and the government, or anyone with a tag reader could identify you from several feet away, some dozens of feet.

While the latest tags still have yet to function without a large antenna (about 1 inch long) making them quite a bit more obvious than a grain of dust, I am sure the day is not far off that this large (in comparison) antenna will shrink down to some unnoticeable grain of evil. When these are forced upon people the end will have probably already begun.

UPDATE:

Apparently while we were asleep, newer chips have been made that are a mere 0.075mm x 0.075mm, and they are embedded into super small antennas that can be read from 1 foot away:
http://www.crunchgear.com/2009/06/02/hitachi-develops-worlds-smallest-rfid-chip/