I first read about Trimark at the Torrent Freak blog. This new anti-piracy solution targets websites and the Usenet by scanning the contents for serial numbers that have been implemented into the music files. An identified serial number would lead to the owner - the person that purchased the music - who will be held reliable for the damages caused by the spreading.
The article did not contain information about the technology behind Trimark other than that the “identification code maintains it’s integrity, despite copying or ripping.” This is a very bold statement and I personally don’t think that such a system will be possible unless they implement it in music that can be purchased in digital form only.