Today on Twitter, Coldplay count down the hours to the first-annual iHeartRadio Music Festival in Las Vegas, where they will perform alongside Jay-Z, Lady Gaga and more, in what is expected to be a one-of-a-kind event. Also in today's tweets, Beyonce's kid sister Solange gets a bit teary-eyed over the Justin Bieber documentary, Lil Wayne sets out for Hawaii and Sean Kingston thanks his lucky stars for friends. See what your favorite artists were tweeting about today!