I was a little apprehensive about upgrading due to the fact that I had originally unlocked with Ziphone, but it turned out not to be a big deal. I had read conflicting information about Ziphoned 1.1.4 phones... Some state you need to start over with WinPWN (I'm on Windows) while others claim that you don't need to do anything special and yet other people will report that you're just plain screwed.
Well here's how I did it... Use this information at your own risk (as did I).
What I had:
Iphone 1.1.4 with Tmobile T-Zones Hack
Originally Unlocked / Jailbroken with Ziphone 3.0
Bootloader 3.9
What I have now:
Iphone 2.0 with Tmobile T-Zones Hack
Bootloader 4.6
I didn't use WinPWN as all the other guides have stated, instead I:
1) Installed BootNeuter 1.0 via Installer.app
2) Launched BootNeuter and changed "Neuter" to "On" and Bootloader to "4.6" -- required a phone reboot (make sure you turn OFF autolock!).
3) Updated iTunes to 7.7
4) Downloaded the custom 2.0 firmware image located here:
http://www.iphone-releases.com/iPhon...ases.com).ipsw (Look for "iPhone 2.0 pwnage on windows" thread, it has a direct download to the firmware, not a torrent)
5) Used Ziphone 3.0 to put the iPhone into DFU mode
6) Opened iTunes and held "Shift" key while clicking the restore button, then selected the 2.0 firmware image.
It took about 10-15 minutes but everything went well without error. On the first reboot BootNeuter 2.0 ran at startup and unlocked the phone. After that I used Cydia to install OpenSSH and the Tmobile Tzones Hack.
I didn't see any errors during any of this... Everything in 2.0 appears to be working fine.