First the iPhone sold out in the U.K. online Apple stores. Now it has sold out in the U.S. Customers attempting to order one are met with a "Currently Unavailable" message. This includes both the 8-GB and 16-GB models. 3G iPhone around the corner?

This latest bit of news is the most recent indicator that a 3G version of the iPhone is ready to hit store shelves, possibly sooner than anyone anticipated. Over The Air reported last week that iPhones have been selling out at European network operators, as well as at Apple's own online store in the U.K. The iPhone has now sold out at the Apple online store in the United States. I called two area Apple stores, and both said they still have stock of both the 8-GB and 16-GB models available. Neither store, however, would say how many units they had left.

Could Apple have misjudged its supply, or the popularity, of the phone ahead of the apparent 3G launch? Personally, I wouldn't advocate anyone purchase an iPhone right now anyway. Why bother? With a much-improved version set to become available in mere weeks, it's not worth it.

But Apple will certainly be missing out on some sales if the phone becomes completely unavailable everywhere. All indicators had been pointing to a late-June release of the 3G version of the iPhone. With supplies running low, I have to wonder if the iPhone will become available sooner, perhaps as early as June 9, when Steve Jobs is set to give his keynote address at the WWDC.

As I've pointed out before, however, no new versions of the iPhone have passed through the FCC Web site. It must do that before it can be sold. It is rare for a phone to announced and approved at the same time. The FCC gets to things when it gets to things, and cannot be prodded by Apple to push its device through the approval process.

Of course, a new shipment could arrive at the U.S. online store and it could begin shipping again.