Saw it a while back. Quite amusing.
The original Jobs/Gates parody battle was from SuperNews.
Less rapping, more funny.
"iPhone, b***h!"
YouTube: video
I've found these the best so far
Vader vs Hitler
http://www.youtube.com/watch?v=AFA-rOls8YA
Einstein vs Hawking
http://www.youtube.com/watch?v=zn7-fVtT16k
Ghandi vs Luther King
http://www.youtube.com/watch?v=-6G6CZT7h4k