Sting, Mary J. Blige join in rendition of 'Signed, Sealed, Delivered, I'm Yours'
Obama speeches also included in box set
Items from Stevie Wonder, Jackson Five will be on display
Soul singer is set to unleash one of his biggest hits again
He's the second person ever to receive award
Artists show their support for Obama in Denver
Soul legend also praises Amy Winehouse at intimate gig
Legend launches dates with intimate London set
Joss Stone and Gomez will also play free event
Legend will kick things off next month