With the iPhone 3G S – the speedier iPhone unveiled by Apple last week - to hit the AT&T stores in the US on Friday, Apple is already warning that that the new offering will likely be sold out on the launch day itself!

Anticipating an iPhone 3G S frenzy, AT&T is already out with a web checklist and pre-order form for customers, in order to help them “reduce wait time on launch day,” with the condition of one iPhone 3G S per person.

To be available in black and white models, like its predecessor, the 16 GB version of the iPhone 3 G S will cost “$199 for new activations and qualified upgrades” or “$399 to purchase an early upgrade”; and the 32 GB version will cost “$299 for new activations and qualified upgrades” or “$499 to purchase an early upgrade.”

The new model is equipped with a 3-megapixel, auto-focus camera, which also captures video, and has voice control for dialing and iPod playback. Other highlights include cut-and-paste controls and MMS visual text messages, to enable users to add pictures and audio clips to text messages.

Yet another new feature of the iPhone 3 G S is the “Find My iPhone” feature - available for a $99-a-year subscription to Apple’s Mobile Me service – that displays a visual map to show the location of the iPhone.