I agree. A year or so after iTunes was introduced, WSJ's Walt Mossberg wrote that iTunes was shouldn't be underestimated, that it was so much more than a music management system--that it was actually a complex and powerful bit of software that would in the years to come dazzle people with new opportunities (think App store) for Apple.
He was right, of course. I see Ping in the same way. It is apple's foothold on the social networking universe. People will start out organizing in friend circles--there WILL be one for Tea Partiers, for example, organized at first around patriotic/jingoistic music, depending on your pov, and other circles for people of other lifestyle/political persuasions. Eventually the content and capabilities of Ping will broaden and Apple will be bragging about its market share as a social network compared to facebook and the rest.