Yes, he's a real person. Here's the video.
Congratulations, Joe. You are now the most famous plumber in the country, thanks to the presidential candidates' repeated references to you and your plumbing business.
No, really. "Joe the plumber" isn't a figment of the candidates' imaginations. He's a real plumber. Here's the proof:
Update: Looks like CBS News Anchor Katie Couric snagged an interview with Joe. Here's that video: