When Apple announced Ping back in September, some heralded it as another brilliant move from Apple that would keep people immersed in the iTunes experience and bolster music sales. Most people, however, didn’t seem to care. Ping is Apple’s social network focused on music — described by Apple CEO Steve Jobs as “Facebook and Twitter meets iTunes”. It allows users to follow friends and artists to see what they’re listening to. More importantly, it allows users to then buy the tracks shared by those they follow with minimal effort. We don’t personally know anyone who uses the service however, and it looks like we now know why. Apple sent out an email to iTunes users today in an effort to remind them, well, that Ping exists. The email states that Ping “already has millions of users” and that it’s “growing fast”, but we don’t recall receiving emails like this when Apple has launched successful products and services in the past.