iTunes Plus offers DRM-free music tracks featuring high quality 256 kbps AAC encoding for audio quality virtually indistinguishable from the original recordingsfor just $1.29 per song. iTunes customers can easily upgrade their library of previously purchased content to iTunes Plus tracks for just 30 cents a song and $3.00 for most albums.
Major record labels have thus far withheld these formats from Apple in an effort to reduce iTunes' marketshare in digital music downloads. 9to5Mac believes that Sony BMG's participation in iTunes Plus will be announced within a few weeks/months. Perhaps MacWorld San Franscisco would be a possible date.