Mobile Marketing Watch has an interesting take on just why smartphones are hammering the carriers' networks. It's a bit more nuanced then you probably expect:

Through its research, Airvana identified a significant mobile network “load multiplier effect” caused by smartphone data traffic on the macro-cellular network.  Airvana engineers comparing data use profiles found that for a given volume of data transmitted, one smartphone typically generates eight times the network signaling load of a USB modem-equipped laptop. Although smartphones may only account for a minority percentage of all devices on operator networks today, they’re always on, moving between cell sites and continually ‘polling’ the network.  As a result, smartphones are already responsible for the majority—two to three times as much as laptops—of the total signaling activity.

Put simply, the nature of smartphones – with their mobile Web-focused design and always-on capabilities are swallowing bandwidth faster than any other device in use on wireless networks today- eight times more than a laptop pulling the same bandwidth from a USB-based mobile broadband connection.

Read more @ Mobile Marketing Watch.