Some would say that many of the women in the above photo are quite beautiful, but in fact, none of them exist. Pierre Tourigny downloaded about 30 pictures of women per photo from a popular internet "photo rating" site, then used free software (SqirlzMorph) to create the virtual women in the composite images above. link [flickr]
Other projects that have attempted to create virtual belles and beaus via morphing technology include Face of Tomorrow and Beauty Check. The Virtual Miss Germany contestant on Beauty Check is particularly fascinating.
I often find that some level of asymmetry, along with look young, leads to a person being labeled as "cute" rather than "beautiful". Ashlee Simpson is a great example. I thought she was as cute as a button before she got her nose job, but now she just looks plain.
And like ToddZ said, the symmetry also makes the faces more attractive. Symmetry is an indication of health and proper development, so from an evolutionary perspective it makes sense that we should be attracted to symmetry so that we can produce healthier offspring!
I also agree that miss “6.0-6.4″ is super cute. Miss “9.5-10″ is stunning though.