Here's another clue that may indicate Apple plans to introduce a new iPhone at next week's WWDC event in San Francisco. Best Buy has issued a memo to its store employees, noting that iPhone supplies are dwindling, and they may run out altogether.There's nothing like a sale to clear out the old stock before the new stock comes in. In this case, though, there isn't much of a sale, and just a petering out of the existing supplies. Best Buy has informed the employees in its mobile stores that iPhone stock is pretty much on the way to zero, and they shouldn't be surprised if they run out all together.

This follows reports from wireless network operators and even mobile supplier Brightpoint that the iPhone 3G has reached its End Of Life. Vodafone Australia said, "We have just been notified that the [iPhone 3G is] End Of Life and that there is only a few weeks stock available from Brightpoint. This is an opportunity to take advantage of these devices whilst they're still available." In other words, if you are in the market for a new iPhone today, you'd best hurry up.

Even AT&T here in the U.S. has said the same thing, and is offering refurbished iPhones, instead.

Given that three separate sources have indicated that iPhone stock is dwindling, we know Apple has to replace it with something. Perhaps we'll find out next week.