SonyBMG, soon to be Sony Music Entertainment Inc, is one of the four major music labels, and features bands and artists like the Ting Tings, AC/DC and Dido. If rumours are correct, then music from those bands and many others will soon be available on the iTunes store DRM-free.
Currently, EMI are the only major label to offer MP3 files on iTunes Plus - Apple's name for their DRM-free, slightly higher quality, offering that costs 25% more per track than DRMed files. If Sony's music is added, it will be a plus for Apple, but they still lag far far behind services like 7digital, who are 100% DRM-free, and remain my a la carte MP3 download provider of choice.
While we're at it, do you know what the most downloaded catalogue song ever on iTunes is? Soundscan, over the weekend, determined that it's the epic "Don't Stop Believin'" by Journey. Classic. I've embedded a video of them playing it live just after the jump. Power Ballads first thing on a Monday morning are just what everyone needs.