Takedown notices are the official mechanism used to report infringing content under the DMCA. They're routinely sent to ISPs, who then typically send a warning of some kind to the individual they determine was responsible based on information supplied by the copyright holder.
No doubt what will attract the most attention, and is certainly the most amusing aspect of the paper, is that 3 laser printers and a wireless access point were the targets of a combined 13 takedown notices. In each case, as well as 5 more where a desktop computer was alleged to have illegally shared files, it was due to intentional misdirection on the part of researchers who wrote "The potential for false positives and implication of arbitrary addresses undermines the credibility of monitoring and creates a significant inconvenience for misidentified users (if not financial and/or legal penalties)."
Despite the report's somewhat humourous point of view, in the end there's not much to laugh about. The researchers concluded "Our results show that potentially any Internet user is at risk for receiving DMCA takedown notices today. Whether a false positive sent to a user that has never even used BitTorrent or a truly infringing user that relies on incomplete IP blacklists, there is currently no way for anyone to wholly avoid the risk of complaints."
Finally Piatek, Kohno, and Krishnamurthy cautioned "Through extensive measurement of tens of thousands of BitTorrent swarms and analysis of hundreds of DMCA complaints, we have shown that a malicious user can implicate arbitrary network endpoints in copyright infringement, and additional false positives may arise due to buggy software or timing effects."
They urged enforcement agencies to adopt a "more thorough approach to detecting infringement in BitTorrent" to avoid the problems described in the paper, but note that it would be significantly more difficult than the way these operations are handled right now.
You can find more information about report at the University of Washington website.