An upcoming update could give GSM iPhones the same mobile hotspot support as on the Verizon edition, a leak today hinted. "Reliable" data pointed to iOS 4.3 making it an official feature for everyone. Greek site iPhoneHellas' information isn't confirmed but was backed by its accuracy in predicting both iPhone 2.2 and iOS 4.0.1 in the past.
The feature may follow the carrier-by-carrier support pattern established with tethering, however. tips to the Dutch site iPhoneClub noted that a user's carrier profile might dictate whether or not the Personal Hotspot settings item shows in the menu. Such filtering would give everyone a common OS but prevent conflicts with AT&T and other carriers that are still undecided on whether to follow suit.
What else would come with iOS 4.3 hasn't been mentioned, but rumors floated in December of iTunes subscription support for periodicals and other recurring downloads. Apple also has to eventually add support for future iPads, but 4.3 may not necessarily be the official release.