It's all over but the singing: Beyonce and Jay-Z last night welcomed their much-anticipated daughter via scheduled C-section, according to various reports. Details are sketchy: The consensus and E! Online say that the baby's name is Blue Ivy Carter; others, including the New York Post, originally had it as Ivy Blue Carter. A rep for New York City's Lenox Hill Hospital tells the Post that Beyonce checked herself in early yesterday evening, and that mom and Blue Ivy are doing fine. The couple's reps are so far predictably mum, but congratulations were making the rounds on Twitter, with Rihanna tweeting: "Welcome to the world princess Carter! Love Aunty Rih."