Around the 6:30 mark, Bebe, the original creator of the song, explains that she was expecting to sing on the track alongside Eminem, however they only kept her high note, vocals that are mistakenly associated with Rihanna
I thought everyone already knew this? If you listen to the demo they're identical (and sound nothing like Rihanna even if you haven't heard the demo, anyway).
What songs would those be? 