I asked Paul J. his ID of this individual, because I've never knowingly seen a mountain mahogany hairstreak before. Although, I did note in the Pinnacles Count about seeing a hairstreak with a blue tail end (just like this one!) and was hoping my count partner from the Sequoias had gotten a picture. Tiny, dark, zippy shadows. The iridescent sheen looks so much like the hedgerow hairstreak I photographed only 2 days before that I can easily see getting them mixed up on the wing from a distance. Up-close and depending on the lighting, it's darker than the hedgerow, without the bright copper color, and has an overall blue cast to the underside wings. Other people note the white flecks in the wings and the pointier forewing tip compared to the hedgerow. I have a hard time seeing other people's descriptions of shapes, so that doesn't work very well for me. With the relative lack of tails, this is apparently a boy.
ps 08/05/14 - Art also pointed out many male hairstreaks have a stigma on the forewing that shows through as a relief. It's absent in females.