Yet another bug to be added to the growinglist of problems with iPhones after the iOS 4.2 update. It seems that iPhone 3G users who have officially unlocked their phones to be used on a carrier that Apple is not partnered with lose their tethering capabilities after they’ve upgraded to the latest version of iOS. This problem doesn’t seem to affect phones that are on carriers contracted with Apple, and iPhone 3GS or iPhone 4 users. This problem could be very annoying because some users who pay their carriers for the ability to tether are paying for nothing. At this point in time, Apple has not acknowledged the problem and there is no easily available fix. The only thing you can do is don’t upgrade to iOS 4.2 if you’re still on iOS 4.1, and downgrade back to iOS 4.1 if you’ve already upgraded. Let’s hope an official fix is released soon.