The ailing Senator rouses thousands of Democratic faithful in the Pepsi Center.
His entrance is met with cheers, applause and whistles-- watch video here.
"My fellow Democrats, my fellow Americans, it is so wonderful to be here. And nothing is going to keep me away from this special gathering tonight."
Vows to be on the Senate floor next January. Says after November, "The work begins anew, the hope rises again, and the dream lives on."
His speaking had been in doubt due to health concerns-- earlier plans called for him simply to watch Monday's tribute.
He speaks after a video tribute and comments from his niece, Caroline Kennedy, who says, "I have never had someone inspire me the way people tell me my father inspired them, but I do now, Barack Obama."
