"Wining Boy Blues" was a song by the famous rag blues piano player Jelly Roll Morton. We're guessing that The Piano Lesson's blues singing, piano playing Wining Boy is named after this song.
The TV movie version of The Piano Lesson, made by Hallmark Hall of Fame, is the only film version of an August Wilson play to date.
The Broadway premiere and film version of The Piano Lesson starred Charles S. Dutton as Willie Boy. (source)
The place where the Southern railroad crossed the Yellow Dog is where Wining Boy says he talked to the Ghosts of the Yellow Dog. This is a real place which some consider "the most important spot in bluesdom." Find out why here.