i shuai dot org

Can Your Printer Identify You?
From this story from the Electronic Frontier Foundation there is a story about if the printer encodes your serial number into paper you print.
Here is an excerpt:

On Nov. 22, 2004, PC World published an online article stating that “several printer companies quietly encode the serial number and the manufacturing code of their color laser printers and color copiers on every document those machines produce. Governments, including the United States, already use the hidden markings to track counterfeiters.” (http://www.pcworld.com/news/article/0,aid,118664,00.asp). According to the article, the high fidelity of outputs from color machines to their original documents suggests that counterfeiters can potentially succeed in creating high-quality counterfeited currency and government documents using these machines. At the request of the United States Secret Service, manufacturers developed mechanisms that print in an encoded form the serial number and the manufacturer’s name as indiscernible markings on color documents. The Secret Service and manufacturers would be able to decode these values from the markings and in the event a color machine was used to print a suspected counterfeited document, these values would be used with customer information to discover the identity of the machine’s owner.

[Extracted From: http://www.eff.org/Privacy/printers/wp.php]

The color would be a bright, hard-to-see yellow. See the whole article for more details, plus test sheets and how you can help.
Some people think this would be good to stop counterfeiters, but I think that these companies have just crossed the thin line between valid tracking and privacy-intruding tracking.