There's another wrinkle with this year's WWDC. In the past, Apple has only had to introduce one type of phone to run on AT&T's GSM network. Starting in February, though, the company added Verizon as a service provider in the U.S. meaning it had to produce an entirely different iPhone model to run on that carrier's CDMA network. Having different flavors of iPhone was a compromise Apple was willing to make to expand its customer base, but it's probably not something the company wants to maintain long term. Already, GSM-based iPhones are running iOS 4.3.3, while the CDMA-friendly models are still at version 4.2.8--that sort of fragmentation is all well and good for Android users, but it's anathema to the way Apple runs things. A major hardware update may have to wait until Apple builds one that's compatible with both AT&T and Verizon networks.

The fact that Apple broke a three-year precedent and didn't hold a spring iOS event suggests that the pace of development might be slowing down by design. That would hardly be out of step with how Apple handles new operating systems. You may recall that after yearly updates to OS X for its first few years of existence, to a less frenetic clip. That was three years after OS X's 2001 debut; maybe we've reached the same point with the iOS platform where annual overhauls aren't as necessary as before.

Still, a few external factors make me think that it would be better for the company to roll out a new version of the iPhone sooner rather than later. Not that Cupertino takes it cues from other companies (or from me, for that matter), but surely Apple executives notice the steady stream of smartphones that have hit the market since the last time they introduced a model. I can't imagine the company willingly sitting on the sidelines while Android phones continue to dot the landscape. More to the point, any iPhone 3G owners who picked up their models in the early months of 2009 are now blessedly free of their AT&T contracts. With a growing number of iOS features unavailable to older phones, those users will be looking to upgrade to a new model--and Apple would do well not to tell them to cool their heels for the next few months as the next iPhone moves from the drawing board to retail shelves. Finally, it doesn't really fit into Apple's m.o. to unveil a new operating system without also rolling out hardware specifically designed to exploit its new features to the fullest.

Apple is likely stick to its pre-announced script for WWDC, talking only about iCloud, Lion, and iOS 5, and it will still be a feature-packed morning. But there's always that One More Thing. A new iPhone may be improbable for all the reasons listed above, but if Steve Jobs happens to have one up his sleeve on Monday, it wouldn't necessarily surprise me.

[Macworld.com executive editor Philip Michaels has an unsettling habit of being wrong in public about these kind of predictions.]