Bobbi Brown has discovered social media and is letting the world know it with a Twitter press conference today. “Beauty bloggers and Twitter followers asking Brown questions and her answers in real-time beginning at 12:30 p.m. The Twitter bit is all part of the new Pretty Powerful campaign that goes livetoday at bobbibrowncosmetics.com/prettypowerful. The program involves 50 “real” women — Brown’s friends, staffers and consumers of all complexions — with before and after photos, video po...