ZiPhone - YES - if you're going to 1.1.4 unlock, but I suppose yes for all firmwares.
iNdependence - NO - your baseband for 1.1.4 will be 4.02.
iJailbreak - YES - almost identical thing to ZiPhone.
Can one upgrade to 1.1.4 w/o downgrading BL? I need unlocking, too.
Ok, you will get a bootloader downgrade with 4.05 when you install 1.1.4.
please note that downgrading your bootloader may void your warranty. however it's not a big issue since iphones don't break in a year when handled properly.
Call me crazy, but I am not too hot on d/g to 3.9. What do you think the chances are that ina day or week we will have a 2.6 ZiPhone that will keep 4.6?