Rumors that Apple will unleash several new iPhone models when it releases new hardware this summer have picked up a notch. The speculation is that the company could unveil a cheaper, lighter iPhone, an iPhone especially designed for business use, and a netbook ?in addition to upgrading its current iPhone model.

Clearly, some of these possibilities could be just wishful thinking. But some make a lot of sense. In an economic recession, a cheaper iPhone Nano-type device would certainly sell well. Netbook computers are flying off the shelves, and an Apple tablet is certain to be a hit.

What I don’t buy is the idea of an iPhone for business users. The current iPhone 3G can already do much of what corporate users want: check stock quotes, dip into corporate e-mail, listen to news podcasts. One sure way to increase the iPhone’s appeal to corporate users is to add a physical keyboard. But Apple’s Steve Jobs has always been against that.