Yeah, this article rang my "tinfoil-hat" alarm pretty loudly too. But the source seemed to be more reliable than most. However, you inspired me to do more checking on this, especially since I'm awfully hard on others here who print paranoid bullshit without close examination. ;)

Another story like this can be found here.

A search of Xerox's pages showed that they do have a technology for printing invisible codes, but there isn't the slightest hint that this is standard equipment, and in fact is quite expensive.

I found this, which contains the following:

Meanwhile, would-be counterfeiters may also find themselves stymied by security devices that appear on some of the equipment used to print fakes. For more than a year Canon Corp., the leading manufacturer of color copiers and a producer of printers and scanners, has quietly incorporated two anti-counterfeiting features into its business products, says David Farr, senior vice- president and general manager of Canon USA, Inc. The copiers include a specially programmed microchip that recognizes the currencies of several countries, including the United States and Japan. If someone attempts to copy the currency, the copier will print a black sheet of paper instead.

A more subtle deterrent imprints a code of the machine's serial number on every copy it produces. The number is encoded in ``microdots'' that can be printed anywhere on the page. ``Nobody even knows these features are in there,'' Farr says. The serial number can be decoded only with special equipment that he declined to identify, which the company provides to the Secret Service and other federal agencies solely for tracing counterfeits to the copier on which they were made.

I haven't seen this from any other source. I tried looking it up on Snopes, but their search engine blows goats.

I do know that Photoshop can embed some kind of invisible "watermarks" in my illustrations, so obviously the software and technology for this is not out of reach.

I would put this in the "interesting, but don't take it to the bank" category.