Metallica drummer Lars Ulrich used to be the loudest opponent of giving away music for free online. But today he joined Napster founder and erstwhile enemy Sean Parker to announce that his band's entire catalog has gone up for streaming on Spotify.

At a Spotify press conference this afternoon, Ulrich and Parker (now on Spotify's board of directors) shared a stage on the occassion of Metallica finally allowing their music to be streamed by Spotify's 20 million users. "When [Sean and I] saw each other a few months ago, we could see that we had been put as adversaries but we had much more in common and sitting down was long overdue," says Ulrich. "We were younger, maybe somewhat more ignorant," Ulrich says of Metallica's notorious showdown with Napster in 2000, when the band filed a lawsuit that ultimately spelled the file-sharing site's undoing. Ulrich said that the whole affair turned into a "streetfight," and that it was "never about money, it was always about control." Five million Spotify users pay for the service, which may have helped convince Ulrich to get on board.  

Metallica acquired all of its masters from Warner Music last week, launching their own Blackened Records label. Who knows exactly why Ulrich has had such a change of heart, but thrash metal fans looking for some heavy headphone music for the office probably don't care either way. Headbang away, Spotify users.