Looking at the big picture long term, it's not hard to see how truly open smart phones on truly open networks could make wireless carriers nervous. Mobile VoIP may someday pose more than a passing threat to wireless voice (if carriers ever stop crippling such apps), while text messaging services may ultimately start taking more serious aim at that the wireless industry's true cash cow: SMS and its huge profit margins. Dan Frommer at Silicon Valley Insider notes that AOL's new AIM client for the iPhone could finally be the start of this shift, given it supports Apple's new push technology:Aside from regulation, there's nothing a broadband ISP executive (wireless or terrestrial) fears more than being a "dumb pipe," over which other service/content companies profit. The fear of lost revenue is why carriers have fought so hard against truly opening up networks and devices, and generally refer to open networks as some kind of unruly wild west where horrible things roam. Push IM clients won't change things overnight, but they may be an early salvo in a much broader evolution.