When Steve Jobs announced their deal with EMI Records to sell DRM free music Apple and EMI were lauded for listening to the cry of the music buying community to remove digital rights management from their products.
With the launch of the service under the iTunes Plus banner it has become clear that while the music files are not crippled by Digital Rights Management(DRM) they are being encoded with the buyer's personal information. Recently Ars Technica, among others, have identified digital watermarks embedded into the music files that includes the buyer's name and email addresses at the very least.
Apple's iTunes Plus service offers music free of it's Rights Management software but at a premium above the 99 cents it charges for the DRM crippled versions.
EFF, The Electronics Frontier Foundation continues to study the files to see what other information is being embedded in the files.
As of this writing Apple has not commented on the issue.