While Alba gets blonder and shorter. These celebs love to change their image. At the Nautica/Details party the ladies debuted their new looks. I think Paris has a wig on since there is no way that her hair got that longover night - besides she loves to play around.
Alba probably did so much damage to her hair recently with the blonder and blonder image and extensions - this look for her is just to get her locks back to normal. Either way she looks great.