Just use pwnage, you can find guides on www.hackthatphone.com
It's a very easy process and works with 2.0.2. As far as I know zipphone is now dead.
andyr did you jailbreak your iphone initially with ziphone? I want to update my 2g model to 2.0.2 but I read somewhere that as I have jailbroke my iphone using ziphone if anything goes wrong my iphone will be bricked. Is that true? Not too clued up on the iphone hack scene so have no idea whether the site was just spouting BS. Also does the new firmware causing shorter battery life?