updated 10:40 am EST, Wed January 12, 2011
Will likely be limited by carriers
All iPhones should indeed get support for creating personal hotspots with iOS 4.3, a BGR source claims. The option is reported to have been found in early code. The OS will allegedly be build 8F5148b, and include v04.08.00 baseband; "technical acceptance" is planned for March.
The ability to actually use an iPhone as a hotspot is likely to vary from carrier to carrier. Verizon is so far the only one to announce support, and carriers are typically reluctant to allow the data use that comes with tethering. AT&T may, on the other hand, feel pressure to enable hotspots to avoid losing too many subscribers to its chief rival.