From PC World :
According to experts, 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.
Peter Crean, a senior research fellow at Xerox, says his company’s laser printers, copiers and multifunction workstations, such as its WorkCentre Pro series, put the “serial number of each machine coded in little yellow dots” in every printout. The millimeter-sized dots appear about every inch on a page, nestled within the printed words and margins.
“It’s a trail back to you, like a license plate,” Crean says.Geek News has more discussion on the topic. The assumption that this was done solely at the behest of the US Government appears to be misplaced, European countries have been in on the action (PC World – DM Europe)
As potentially creepy as it is to have these tiny identifying codes in printers (scanners have had them for a long time), Wizbang regular Jim Kouri notes in an article on drug traffickers and organized crime:
Advanced design, copying and publishing technology is enhancing the capability of international criminals to produce high-quality counterfeit U.S. currency and financial instruments. For example, the percentage of counterfeit U.S. currency passed in the United States that was produced using inkjet color copiers has jumped from 0.5% in 1995 to 39% so far in fiscal year 1998.
The researchers quoted in this PC World story have determined that subtle manufacturing imperfections in cheap inkjet printers make it possible to fingerprint those devices as well – though not to the same degree as the lasers…