More than one million people joined Ping, Apple's music-based social network, in less than 48 hours

"Apple® today announced that in less than 48 hours since its launch on Wednesday, more than one million users have joined Ping, its new social network for music which lets users follow their favorite artists and friends to discover what music they’re talking about, listening to and downloading.
“One-third of the people who have downloaded iTunes 10 have joined Ping,“ said Eddy Cue, Apple’s vice president of Internet Services. “As many more people download iTunes 10 in the coming weeks, we expect the Ping community to continue growing.“"
Source:  Apple press release, 3rd September 2010