so it will allow me to upgrade from 4.0.2 to 4.1 also correct?
can this same process be done with 4.2? to keep the baseband at 1.59?
thanks again for all the help
Not with pwnage tool. It hasnt been updated yet to work with 4.2 and there is no JB yet for 4.2
You can update to official 4.2 while keeping your baseband the same by running tinyumbrella in the back while its updating. But you wont be able to JB it yet or unlock so I'd suggest you wait and be carefull so you dont lose your unlock ability.
I know this trick worked for iPhone 4's when updating to 4.1, but it is confirmed that updating to 4.2.1 using this method will still prevent the modem firmware from being upgraded?
Yes, the tinyumbrella method will work with any firmware update.
It blocks the communication between the phone and apples servers so everything gets updated but the baseband on iphone 4's.
Then at the end it throws an error message cause firmware and baseband dont match. You just gotta kick device out of recovery and you're good.