It seems to be getting harder to find the iPhone in Europe these days, a possible sign that the 3G version is close to release.

For a period of time on O2's Web site Thursday, a message stating the iPhone was "no longer available" greeted users. This had changed by midday US time, when the 16 GB was shown to be again in stock.

This periodic unavailability matches reports from other retailers across Europe that their iPhones are either out of stock or in low supply. Carphone Warehouse is sold out of the 16 GB phones, and earlier, both they and O2 stopped selling the phone due to it being "discontinued."

Apple regularly discontinues current products ahead of launches of their replacements. Typically shipments of the product stop rather abruptly and it is allowed to sell out, thus allowing the company to sell through most of its inventory at the full price rather than at a discount.

It is believed that the next generation iPhone will begin selling sometime in late June, roughly a year after the first model was launched. However, it seems possible the device may first make its appearance at the Apple Worldwide Developers Conference on June 9.