Borrowing a Stairway to Heaven : did Led Zeppelin rip off a riff?

More than 40 years after the release of Stairway to Heaven, English rock band Led Zeppelin are facing allegations that its iconic guitar riff was stolen from Taurus, a song released in 1968 by the American rock band Spirit. The two riffs are clearly similar: they share a four-bar instrumental guitar passage with similar harmony, tempo and stylistic features. Businessweek has created a short game where you can test your skill at telling the two apart...