Beyoncé Knowles gave birth to a baby girl today in New York! She and Jay-Z reportedly named their daughter Blue Ivy Carter. Rihanna shared in the excitement this evening tweeting, "Welcome to the world princess Carter! Love Aunty Rih" while their friend Gwyneth Paltrow said, "Welcome to the world Blue! We love you already." We can't wait to see pictures of adorable baby girl Blue — congrats to Beyoncé and Jay-Z on this extra special weekend!