Sony BMG could be about to drop DRM, the copyright protection that stops tracks being copied between devices according to a report on BusinessWeek.com.

The magazine is reporting that; "Sony BMG, a joint venture of Sony (SNE) and Bertelsmann, will make at least part of its collection available without so-called digital rights management, or DRM, software some time in the first quarter, according to people familiar with the matter."

The move would mean that the big four music labels have all dropped DRM music.

The news follows Warner Music Group's announcement in December that it would sell DRM-free songs through Amazon.com's digital music store and EMI and Vivendi's Universal Music Group announcing their plans for DRM-free downloads earlier in 2007.

The move comes also a year after Apple CEO Steve Jobs wrote an Open Letter to the music industry hinting that it would open up its iTunes music store to be compatible with other players such as Microsoft's Zune and Sony's Walkman phones if the music industry dropped its insistence on making sure music files are locked with copyright protection software.

We will keep you posted.