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Brits hoping to buy an Apple iPhone this week (or next week, or the week after that) are out of luck. O2, Apple's exclusive carrier in the UK, has run out of iPhones. There's reportedly not a new phone to be had in the British Isles right now, as everyone eagerly awaits the 3G version, rumored to be launched this summer. (No doubt there are a few barely second-hand iPhones available out there for the right price.)

And Americans hoping to blow their $600 tax rebate checks on new iPhones might be in for a shock as well. Apple sales reps told PC World last weekend that both the UK and U.S. online stores are sold out. (Further evidence here.) Some iPhones should still be available in Apple stores, but all the disappearing acts have talk of the 3G phone going into hyperdrive.

In the current issue of FP, I have a short piece on the iPhone grey market, the million+ iPhones that have been unlocked for use all around the world. There's evidence that Apple not only didn't anticipate the extent of the underground market, but that as soon as it became apparent, they've used it to their advantage to test market in countries where the phone hasn't yet launched.

Their exclusivity agreements - with AT&T in the U.S., O2 in Britain - were always something of a puzzle, and it looks as though Apple is abandoning them as it becomes apparent that people are determined to get around them. A string of announcements in recent weeks suggests that iPhones will officially be available on a number of carriers in Australia, India, and Italy, among others. Can the U.S. be too far behind?