First off, Business Week is on some powerful crack that they should share with me if they honestly think Apple can build a national network to rival the likes of Verizon or ATT for just "a few hundred million" dollars. They must be referring to something else (which I'll get to in a moment), 'cuz Verizon and ATT spend in excess of
$6 BILLION on their networks
each year, and that's just to expand and maintain them, not build them from the ground up, as Apple would have to do. Not to mention that such stuff is far from their core competency.
So I don't think Apple is trying to be an all-singing, all-dancing national carrier.
What I think is really going on is that Apple REALLY wants to sell HD content over iTunes, and is very frustrated by the lack of infrastructure to do that.

DSL and cable broadband is way too slow... even at 6 Mbps it would take you several hours to dload a feature-length HD movie. Fiber to the home is faster, but the deployment is slow, due to the nature of such deployment (dig up everything) and the very high last-mile costs.
So what's the solution? Wireless.
Using 4G technology (WiMax, EVDO RevC/UMB, LTE), you can allegedly get data speeds in the 50-280 Mbps range... FAR faster than what most ppl have currently at home. And of course you side-step those huge, pesky last-mile costs, and the slowness of deployment that comes from having to dig up Mrs. Jones' lawn to lay down fiber.
Sprint and Clearwire are already laying the groundwork for this sort of thing with their WiMax network buildout. Apple could partner with them for content delivery (and maybe still will in some regions where an alleged Apple 'content delivery network' is not built out yet), but I guess Steve is not big on middlemen, as they'd of course take some of the profits and could potentially prevent Apple from doing things Apple's way.
Another advantage of this is, if voice is not the primary service, your network build-out can be much more limited geographically, which helps keep a lid on costs. If you were a voice carrier and your network only worked in, say, 100 or so densely-populated urban metropolitan areas, people would LAUGH at you and rightly say that your coverage sucks ass. But if you're mainly about getting content to the home in urban areas, then you're basically like cable... some guy living out in the boonies can't get service? Oh well, tough luck, guess he'll have to get a satellite dish or something.
It's a bit like what was already done with MediaFLO... build a national network (of limited geograpical coverage) for content delivery.
So, next you might be asking, "Well, what if Apple also wants to offer significant voice services too? Wouldn't their very limited coverage hose that? People would still have to get an ATT contract too AND pay Apple for their service, WTF?"
Not necessarily. Carriers have what are known as 'roaming partners'. If you travel outside your home carrier's coverage area, you can still get service by 'roaming' on a partner carriers' network. Verizon, for example, has Alltel, Sprint, US Cellular, and several other carriers as roaming partners. ATT and T-Mobile help each other out. Sprint has a number of partners. You get the idea.
So, you'd use Apple's network for voice while you were in town... go anywhere else, and for voice you'd roam on ATT. Or T-Mobile. Or whomever. Nice part, Apple's still calling the shots.
.