Beware of downgrading bootloader to 3.9 using ZiPhone, it is irreversible. You might end with that bootloader forever!! iPlus uses a fakeBL which is reversible! Don't ever restore to 1.0.0 or 1.1.1 though, it will hurt your iPhone for sure!
Visit http://windows-mobiles.com/?p=221 for details!
Want to help support Gadget Hacks and get a great deal on some sweet new tech? Check out all the deals on the new Gadget Hacks Shop.