We've seen how Twitter peaks during major events (like the Olympics or during major TV episodes). I can see Apple eventually wanting to be the source for that info. Then again, they'd have to open it up a lot more and get it on other systems. Ping for PC, Ping for Android (GoogleTV?), Ping plugins, and so on. Which would all eventually lead to the iTunes store...
And what if they then struck marketing deals with a place like Amazon or Zappos? Ping "I like her shoes" and it recognizes that with a "buy" button linking to Zappos and the same shoes.
We've seen how Apple starts small and grows features much bigger than the original intention. We've also see how Apple has transformed themselves from Apple Computer Inc to just Apple (and all that that means).
While Ping certainly sucks now I believe they are committed... and they have a plan.
I think Ping is a "Trojan horse" to enter the Web space without causing too big of a scene. They are testing a few theories out in iTunes before dropping the bomb in January with their next batch of products. Apple is historically cunning and sly in this way. No one can fully guess their next batch of moves.