Umm, no, not the guy who invented the steel plow -that's what I first thought too. Jethro Tull is a British prog rock group from the 70s (yeah, big hair and everything), perhaps best known for their "mother of all concept albums," Thick as a Brick. Like other progressive rock groups of the time, (Pink Floyd, Yes, Genesis) Jethro Tull sought to elevate rock music to new levels of artistic credability. This "elevation" in artistic credability often involved "concept albums", which -according to wikipediea- made unified statements, via an epic story or overaching theme for the album. I think Jethro Tull may have taken this to the extreme...
Look out John Cage, Thick as a Brick contained only one song that spanned a total of 43 minutes and 28 seconds (that's like 4:33 ten times). The recording used extensive overdubs and splicing to create two continuous record sides, and was finished in about a week with the group working diligently and freverently in their practice sessions. With influence from Monty Python's Flying Circus TV show of the 70s, it's without surprise that the group describe live performances of Thick as a Brick as "nerve-wracking and exhilarating, requiring much concentration" (and caffeine, I'll bet).
In addition to the album's unique song list, it also became famous for it's cover art. Done in a collage of a mock newspaper (complete with a crossword puzzle, even!), the cover depicts stories of the bizarre and absurd, and though I personally think the newspaper pages were too sensational to be mistaken for legitimate, apparently there were many who thought a real back-issue of a newspaper had been used. You can imagine what a stir that caused :)
Oh, and the picture up top? That's Ian Anderson of Jethro Tull playing the flute while wearing what looks like spandex.