Before you get too excited, though, hang on: For most users, this move isn't as magical as it may sound.

First, to be clear, an iPhone being unlocked simply means that the device can be used on any supported network; up till now, all Apple phones sold in America have been tied to one specific carrier, be it AT&T or Verizon. An iPhone being unlocked has nothing to do with on how you use the device, what apps you install on it, or anything else related to the iOS experience; carrier agnosticism aside, an unlocked iPhone looks and acts just like any other iPhone you'd buy.

(It's also worth noting that the notion of an unlocked iPhone itself is nothing new; it's merely new to the U.S. Apple has sold unlocked iPhones in other countries for some time.)

The real buzz-kill with Apple's new unlocked iPhone, though, is that its key benefit won't actually be beneficial to you unless you do a lot of international traveling. The reason: The unlocked iPhone functions only on GSM carriers. In the United States, that means you're looking at AT&T or T-Mobile.

But wait -- there's more. T-Mobile's data network doesn't actually support the iPhone 4. So if you were to try to use an unlocked iPhone on T-Mo, you'd be stuck surfing the Web at turtle-like speeds on the carrier's rusty old Edge network. That's certainly no good.