There've been lots of pop stars who turned 50 this year—Madonna, Michael Jackson and now Britney Spears!!!Just kidding. Britney's 27 today, and her b'day coincides with the release of her sixth studio album, Circus. To celebrate, she performed "Circus" and "Womanizer" on Good Morning America today.
She also got some special birthday wishes from Hugh Jackman, Reese Witherspoon and Taylor Swift. Check it out: