On iPhone demographics, the report said they're similar to that of other smartphone users:

"They are more likely to be: male, aged 25-34, earn more that $100,000 and have a college degree, than the average mobile subscriber."

About half used their iPhones to access blogs or social networks, and just under a third used them to watch videos.

Users of the iPhone are also more likely to listen to music on the device -- 74.1 percent do, compared with an average of 27.9 percent among smartphone owners. That isn't too surprising since the iPhone evolved from the iPod, and the majority of iPhone owners live in the Apple universe: 84 percent also own iPods.

The most provocative findings were farther down in the M:Metrics release, where the firm said another key to these trends is the iPhone's mandatory unlimited data plans.

"In addition to the attributes of the device itself, another important factor to consider is the fact that all iPhones on AT&T are attached to an unlimited data plan. Our data shows that once the fear of surprise data charges is eliminated, mobile content consumption increases dramatically, regardless of device,'' analyst Mark Donovan said in the release.

Maybe next time they'll provide a comparison of mobile data consumption among consumers with unlimited data plans, regardless of device.

I wonder if these trends will lead carriers to bind more devices to unlimited data plans; maybe that's the next step now that most have $99 flat-rate offers.

Then again, M:Metrics said the most-used iPhone content application is its music player, which doesn't require a data plan at all.

Here's the key chart; the smartphones here include devices running Symbian, RIM, Windows and Apple operating systems.