iPlus is a *fully automatic* tool for setting up your iPhone! For Windows and Mac OS X (intel/PPC)

It will downgrade the bootloader, unlock, jailbreak and activate the iPhone. And even better, it will also install the most important and common packages as well as several fixes, with a custom payload for installing other packages.

Bootloader downgrading uses BL 3.9FakeBlank, so it is fully reversible.