Whitney Houston would be celebrating her 50th birthday today. Sadly, one of the greatest voices of our time died tragically on February 11, 2012. Since her untimely passing, Houston's legacy has been celebrated and upheld all over the world. She is indeed gone but not forgotten. From Glee to the Grammys, Oprah to the Obamas, here's how the world has paid tribute to Whitney Houston since her death.