A report that came out today says a majority of color laser printer manufactures are using technology that leaves microscopic yellow dots on the pages you print. The information in the yellow dots varies, some have just the serial number of the printer and others also have the date printed. Since color laser printers are coming down in price we are starting to find them in more homes, which is making privacy advocates worry.
Advocates of the technology say it is only used in counterfeit cases and law-abiding people have nothing to worry about. Supposedly the Secret Services are the only authorities able to read the codes, but I am sure there other people out there working to crack it.