Download.com site feedback forum: Software publishers tracking users?

Recently, I received this email from CNET user Nando P.:

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I wanted to ask you a question regarding P2P programs and its legalities. I know that downloading certain files is an illegal activity but cant a company or artist that has their product illegally somehow track you down? A couple of months ago I had downloaded software and the company who owns the software contacted my ISP, stating that they saw that I was sharing the file by looking up my IP address. Since then I havent really downloaded anything but it begs the question: can anyone track your IP or identity when using bit torrent, Azureus or programs of the like?

Thanks in advance for helping me out with this concern.
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The short answer is: sort of. As far as I know, you can not be tracked for using a particular program by a 3rd party without the program publisher's consent.

However, most torrent apps today do let you see the IPs of who's helping to share the file being downloaded. So in theory, a publisher could track that, but it would require finding and opening the torrent in question. That seems like a lot of effort to me, given the volume of torrents on the Web and that most torrent communities require registration.

It seems more likely that you could be tracked by using a cracked program that regularly "talks" to the publisher's server or site. There is the issue, however, of ISPs relinquishing user privacy protections to avoid being litigated against, which means that users with lots of download traffic will stand out as red flags to investigators.

Still, I'm not an expert on the myriad ways that users can be hunted down. Anybody else want to chime in?

-Seth