During the Verizon iPhone announcement earlier today, the company revealed that the CDMA iPhone 4 model would ship with “Mobile Hotspot” capability. Verizon representatives referred to this capability as an “App” that would be preloaded, however during hands on testing with the press it was discovered that the Mobile Hotspot feature is actually part of an unreleased version of iOS, referred to in the operating system as “Personal Hotspot”.
Test models being demonstrated for the press earlier today were running iOS 4.2.5; currently the newest version available for GSM iPhone models on AT&T and other carriers is 4.2.1.
Other screenshots posted by Engadget show the Wi-Fi tethering feature is an expansion of the existing Internet Tethering feature already available, however the current version of iOS only supports tethering over Bluetooth or USB.
It is highly likely that a future build of iOS for existing GSM iPhone models will include the new Wi-Fi tethering feature as an evolution of the Internet Tethering feature already present.