According to a Boy Genius source, and as reported yesterday, iOS 4.3 will definitely be coming to all iPhones and include the Hotspot feature which we saw at the Verizon event yesterday. Accoring to the source, the OS version will be 8F5148b and will have a baseband 04.08.00.
The release will not be until sometime in March however; so do not expect it to hit GSM devices as soon as the Verizon iPhone is launched, we are going to have to wait a little while longer. Also like we said yesterday, we imagine that the feature will be very dependent on your carriers approval, as will any surcharges for it. Maybe AT&T will take the opportunity to be an early adopter to keep existing customers and attract new ones too, here's hoping!
Just as a refresher, the Hotspot feature will allow up to five Wi-Fi devices to connect to and share your iPhone's cellular data connection.