MacRumors.com

TheRegister.co.uk claims that Apple is currently circulating prototype iPhones with physical keyboards amongst some mobile carriers to gauge demand for such a device.

actual prototypes - not just mockups - have been sent to senior executives at some operators. I'm not allowed to even hint which operators... but I can report that the keyboard has "issues" which are not yet resolved.

The author believes that despite Steve Jobs' open criticism of the fixed buttons on existing smart phones, that he is currently exploring keyboarded iPhones. The design is said to be a "slider" type design where the keyboard would slide out behind the screen. The reason for the interest is an attempt to further penetrate the enterprise market where physical keyboards are the norm.

Worldwide, it has not escaped the attention of mobile network execs that the bulk of corporate sales are not into the executive corridor. Rather, they are phones which are provided for staff, and the vast bulk of them have full-QWERTY keyboards - and all the best-selling ones, Nokia, Sony-Ericsson and HTC alike, have slide-out keyboards. The popular Danger Sidekick, too, has a slide-out (spin-out) QWERTY keyboard.

Of course, even if such prototypes exist, there's no guarantee that Apple will actually release such a design.