Good news! Apple's (Nasdaq: AAPL) Ping -- the social-music network that Cupertino's sultans of style embedded into iTunes last week -- notched a million users in less than 48 hours.

Bad news! Earlier in the week, Apple had hyped Ping's chances by alluding to 160 million iTunes users worldwide. In other words, less than 1% of its users hopped on.

Good news! Ping is only available to folks who download the latest version of iTunes. Just 3 million users had upgraded to the latest update at the time of the press release, so a third of the eligible Ping members did, in fact, kick Ping's tires.

Bad news! Don't expect a third of all iTunes users to be on Ping by the time they all upgrade to iTunes 10. Many of last week's updaters probably did so just to check Ping out.

Oh, and it naturally remains to be seen whether those users will stick around.

Ping faced its share of pin-popping critics last week. After all, just 14 artists were available to follow. They represented a diverse selection -- from Linkin Park to Yo Yo Ma -- but they obviously weren't enough to appeal to the indie-embracing music lovers who would be obvious early adopters. Apple has quickly ramped up the number of artists sending out status updates and snapshots, with dozens of available artists as of last night.

The artists will keep coming, especially once they realize that Ping isn't a social network with a music bent, along the lines of News Corp.'s (NYSE: NWS) My Space Music, or even a music-discovery engine in the mold of Pandora or CBS' (NYSE: CBS) last.fm. With more "buy" buttons than a farmer's market, this is really a social e-tail network in disguise.

The next few months will be interesting, as artists arrive with amps and anecdotes. Will that be enough for consumers to stick around, putting up with the commercialism and the 30-second song samples? Heck, even Best Buy's (NYSE: BBY) Napster provides entire lo-fi streams for free!

Apple can't relax just because it's the country's top music retailer. Google (Nasdaq: GOOG) and Yahoo! (Nasdaq: YHOO) have mostly belly-flopped in their efforts to transform their popular e-mail platforms into social networks. Apple's e-tail bent also brings to mind the cautionary tale of Wal-Mart (NYSE: WMT). The world's leading retailer knows how to turn inventory at attractive price points, but it's been one joke after another in social media.

If Apple intends to make a blatant push toward using Ping as a way to sell music, I think it should give users the means to monetize their participation. Apple has a great shot at expanding its already massive digital music sales through Ping -- as long as it realizes that artists' pushing means nothing if consumers aren't pulling.

Have you checked out Ping? Share your thoughts in the comment box below.