[thelibrarian]

I was wondering exactly the same thing, because you do need a model release from all identifiable people in a photo if you wish to use it for non-editorial commercial purposes. Courts have ruled that "identifiable" does not necessarily mean "can see their face" - if you can see any significant part of a person, you need to get a model release before it can be used commercially (e.g. in an ad).

You do not need a model release if the photo is taken for artistic/personal reasons (even if prints of the photo are sold as artistic items).