SIGH
How many times do I have to tell you guys the same thing!
ZiPhone is NOT REVERSIBLE unless you use pwnage to reverse it!
iLiberty/iPlus is reversible but you may as well use pwnage.
furthermore ZiPhone is dangerous as it unlocks and jailbreaks at the same time which if it goes wrong will break your phone.
My advice if you can't handle pwnage is use iLiberty+ as its the safest method.
Below is a iLiberty+ tutorial:
http://www.hackthatphone.com/114/iphone_iliberty_windows.html
For Pwnage read my FAQ! Then you can follow its steps or use the same tutorial site:
http://www.hackthatphone.com/114/iphone_pwnage_mac.html
Pwnage right now is Mac ONLY - a windows version WILL be released soon...