To be honest, this really should not be a surprise to anyone. A recent research paper has looked at how torrents can be and are being monitored. As torrents are often associated with pirated media, it is not unexpected that groups would try to monitor their use, but exactly how this is done is curious to researchers.
Earlier research has shown that indirect monitoring methods can be and have been used to collect IP addresses of torrent downloaders, but now researchers are considering direct monitoring methods. Indirect monitor simply collects information from the torrent's swarm while direct monitoring can be involved. This could mean the monitoring client announces itself for a peer list to create outgoing connections or that it sits there and waits for incoming connections. Either way, the researchers believe they were able to identify monitors as the information they provided, when asked, was inconsistent.
The information the researchers collected about monitoring is not enough for them to conclusively state if copyright enforcement companies are indeed directly monitoring torrents. However they did find that only the top 100 torrents on The Pirate Bay were actually being monitored and public domain files were never monitored. Also, the information a torrent monitor collects, is likely not enough to go after an alleged pirate in a court of law. Instead this monitoring is probably to determine the scale of potentially illegal download activity.