Stars Congratulate Kate Middleton, Prince William on Birth of New Princess

 Hip hip, hooray! Kate Middleton and Prince William added some pink to their lives on Saturday, May 2 -- and they aren't the only ones over the moon about it. From the moment their princess arrived, to when the royal couple left St. Mary's Hospital with their new princess, celebrities have been reacting about the news via social media.

Middleton and Prince William's daughter -- Her Royal Highness, Princess of Cambridge -- is now fourth in line to the British throne, right behind big brother Prince George. Some of the stars excited about the new addition (oh, the clothes she'll wear!) include Ellen DeGeneres, Elizabeth Banks, and the princess' birthday pals -- The Rock and David Beckham!

"Tough Taurus' (including the #RoyalBaby)," the former wrestler tweeted Saturday. Beckham, who attended the couple's April 2011 nuptials, added: "Incredible news. I couldn't be happier for William and Kate. Happy to hear that mother and daughter are fine." He teased: "It's not a bad day to be born."

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President Obama also released a statement. "Michelle and I are delighted to congratulate the Duke and Duchess of Cambridge, her Majesty the Queen and the Royal Family, and all the people of the United Kingdom on the birth of the Royal Princess," he said. "On behalf of the American people, we wish the Duke and Duchess and their son George much joy and happiness on the occasion of the arrival of the newest member of their family."