Through iTunes Plus you can preview and buy tunes in a higher-quality 256Kbit/s AAC encoding, DRM-free format from participating music labels, including the entire EMI back catalogue. These tracks have no usage restrictions.
The iTunes Store will continue to sell songs in the 128Kbit/s AAC bitrate encoding with DRM for 79p, as well as higher quality iTunes Plus versions for 99p where available. iTunes customers can also upgrade their existing library of previously purchased EMI content to iTunes Plus tracks for 20p per song and £2 for most albums.
The first time you buy an iTunes Plus song, you specify whether to make all future purchases iTunes Plus versions (where available). You can change this setting by accessing your account information on the iTunes Store. The tracks bought through iTunes Plus replace the lower-quality versions of the track.
Despite the software update, the iTunes Store itself does not show any DRM-free music currently available for purchase. But this is likely to be added soon.
The new version of iTunes is available to download here , unless you've already done so through the automatic Software Update.