Apple may be plotting a low-cost iPhone--most likely the 3GS--in a move to tackle emerging markets, prepaid plans, and midmarket customers. If this working-class iPhone hits the market it will be disruptive to Android as well as Research In Motion, which is living off its low-cost Curve.

Jefferies analyst Peter Misek works through the math and concludes that Apple can hold profit margins as it increasingly tiers its iPhones. At Apple's developer powwow next week, the company is expected to highlight the iPhone 4S update. An iPhone 5 will come in mid-2012. However, the most disruptive move would be the iPhone for the prepaid masses. Note that prepaid is the only part of the wireless market that's poised for growth and Android devices and RIM's BlackBerry Curve occupy a lot of shelf space.

Read more of "A working class Apple iPhone would disrupt Android, RIM, Nokia" at ZDNet.