So now that you have iTunes Plus that means you can go ahead and download DRM-free songs. Awesome, right? Yes, it's very awesome. But if you thought that meant you could now buy songs from iTunes and then torrent them to help your ratio at Senor Sleazy's Pirate Palace, you might want to hold off.
Turns out that your account information is embedded in every DRM-free AAC file you download, so if your purchased songs somehow get distributed all around the Internets, they'll be able to easily see who the culprit was. But you wanted DRM-free tunes so you could play them on multiple devices and copy them for personal use, not for piracy, right? Right guys?