iPhone Dev Team has just released a bug fix version of PwnageTool 2.2.1. This is a minor update fix a bug related to Simple Mode. Earlier, iPhone Dev Team quoted that you should not use “simple mode” to jailbreak iPhone firmware 2.2:
?Simple Mode? in PwnageTool currently only works for the iPod Touch. To use PwnageTool for iPhones you will need to use ?Expert mode?. This is a workaround while we make an update and fix this issue. In order to do this you will need to navigate to the ?General? window and change two things: Deselect ?activate? ONLY if you are normally able to activate through iTunes (but if you wish to ?hacktivate? the iPhone using PwnageTool then leave it selected). You will also need to change the partition size to about 1000MB (type in the value or use the slider).
?Hactivate? means to activate the iPhone yourself without Apple. This is used if you live outside an officially supported region and cannot activate the phone using iTunes.
And, now with PwnageTool 2.2.1, you may use Simple Mode for the jailbreak. For those who have downloaded PwnageTool 2.2, please download the latest version of PwnageTool here.
For details about jailbreak of firmware 2.2, you can refer to the previous post.
Update: You can refer to the updated guide of PwnageTool to jailbreak iPhone firmware 2.2. The guide applies to both iPhone 2G & 3G.