New York Times reports:

In the last few months, trade groups representing music publishers have used the threat of copyright lawsuits to shut down guitar tablature sites, where users exchange tips on how to play songs like “Knockin’ on Heaven’s Door,” “Highway to Hell” and thousands of others. The battle shares many similarities with the war between Napster and the music recording industry, but this time it involves free sites like Olga.net, GuitarTabs.com and MyGuitarTabs.com and even discussion boards on the Google Groups service like alt.guitar.tab and rec.music.makers.guitar.tablature, where amateur musicians trade “tabs” — music notation especially for guitar — for songs they have figured out or have copied from music books. On the other side are music publishers like Sony/ATV, which holds the rights to the songs of John Mayer, and EMI, which publishes Christina Aguilera’s music. “People can get it for free on the Internet, and it’s hurting the songwriters,” said Lauren Keiser, who is president of the Music Publishers’ Association and chief executive of Carl Fischer, a music publisher in New York.