You're not paranoid:Your printer is tracking you!

It seems that at least some color printers sold in the United States print almost invisible little yellow dots on every page that can be read by the Secret Service to determine the date and time when the page was printed, along with what appears to be a serial number for the printer.

Of course, this makes those printers a spectacularly bad choice for counterfeiting money or other financial instruments, but one can imagine other uses for the marks, such as tracking down anonymous whistle-blowers...

Reported by the Electronic Frontier Foundation, and further commented on by Ed Felton.