Apple's iPhone is definitely not pulling a Zune: Unlike Microsoft's media player, the iPhone is flying off store shelves. The iPhone is selling so well, in fact, that as of Thursday morning, Apple's Shadyside store in Pittsburgh, PA, was the only location in the United States that still had any left in stock. Apple's iPhone availability checker showed that every other Apple store in the country was sold out.

Apple hasn't stated how many iPhone units were shipped to its retail stores, but the supply it did have lasted just short of a week. As of Tuesday, July 3, upwards of 95 Apple Store locations had sold out, and only two days later, that number has climbed to 163.

Presumably, the Shadyside Apple Store will sell out before the end of the day, leaving anyone else that wants an iPhone to either wait for additional units to be delivered to stores, or to pay inflated prices on eBay.

Apple's combination iPod and smartphone retails at US$499 for the 4GB model, and $599 for the 8GB model. On eBay, however, 8GB models can be found for $1,099.99.

Apple has not stated when stores can expect to see their iPhone inventories replenished. Currently, Apple's online store is showing a 2-4 week wait for both the 4GB and 8GB models.

The iPhone was introduced on Friday, June 29, at 6PM local time at Apple's retail locations as well as AT&T stores.