Last night, I was fortunate enough to see Melvin Van Peebles' Sweet Sweetback's Badassssss (there doesn't seem to be a canonical spelling for this word) Song : The Musical, as part of the Apollo Salon series. (It was a small room - maybe 100-200 people).
(the Apollo salon series presents still-in-development productions, I suspect to get an idea for audience reactions, as well as maybe to get people to see works that might not get finished. You can surely read more about it at their web site than I know about it.)
At the beginning, Melvin actually got on stage and did a little speech - he explained that he'd always envisioned Sweetback as a musical, so this was a great opportunity for him - if almost 40 years late. The production was done by the Classical Theater of Harlem, who had been doing a very good staging of his Ain't Supposed to Die a Natural Death in previous years (I recognized a few of the cast members).
The transformation from movie to musical isn't as drastic as it sounds at first - the original movie did not have a lot of dialog, and could easily be viewed as an extended instrumental music video. So, replace the instrumental music with actual songs, and you've got Sweetback: The Musical.
I recognized a few of the songs that were done in the musical (like A Birth Certificate Ain't Nothin' but a Death Warrant Anyway, off of What the... You Mean I can't Sing? ), and in this production, in these cases, the singers actually sang along with the original recordings (with Van Peebles' singing); the writing of the musical is finished, but the production is far from it.
Van Peebles was able to grab the audience right away - an extended introduction of young Sweetback, sung by the five 'whores' (one of which takes his virginity), the virtues of his 'abilities', and what could be in the future for him (maybe even president! no, he is black after all). Using (more) humor (than the movie), it's easy to become invested in the characters.
The plot of the musical is the same as the movie, and works as a musical (it may even be more accessible in this form - whether it's the additional lyrics, the humor, or the stage prescence is up for debate). If this becomes a full-fledged production, I unreservedly recommend it for anyone who'd even bother reading this entry.