And California is not alone. There are no 8 GB iPhones to be had in Miami, Boston, Chicago or Denver. The only store in New York City that carries them is the glass cube on Fifth Ave. If that store runs out, New Yorkers will have to drive to Syracuse, Atlantic City or out to the middle of Long Island. Either that or settle for one of the higher-priced 16 GB models, which are still available in most Apple stores.

By Friday night, only 36 of Apple’s 197 U.S. retail outlets still had 8 GB iPhones in stock, down from 46 on Thursday. The situation is reminiscent the period after the 3G’s launch, when Apple couldn’t make the things fast enough. By mid-August, however, supply and demand had reached a rough equilibrium.

[UPDATE: Either Apple shipped a ton of iPhones overnight or someone fixed its availability widget, because by 9 p.m. Saturday the situation had reversed: all but 14 Apple stores now report that they have 8 GB iPhones in stock.]

What’s going on now? There are several theories. One is Apple has diverted supply to Best Buy (BBY), which started carrying the iPhone in nearly 1,000 stores on Sept. 7 (see here). Another is that Apple is getting hit by a wave of first-time buyers, those most likely to be attracted by the $199 price point. A third theory — which may be wishful thinking — is that Apple has stopped production of the 8 GB model in preparation for some kind of memory upgrade. 16 GBs for the price of 8, perhaps?

Whatever the truth, it seems likely that Apple (AAPL) will be able to include in its earnings for the fourth quarter — which ends in 10 days — nearly every 8 GB iPhone built, because there sure aren’t many sitting in inventory.

You can check the supplies of iPhones at your local Apple store using the company’s availability widget after 9 p.m. the night before.

[Thanks to the Apple watchers at The Mac Observer’s Apple Finance Board for the tip.]