The iPhone DevTeam have released the new PwnageTool that supports the new 2.0 firmware. Currently, it is for Macs only. To download it, go here. It supports both the first generation and 3G iPhone, although unlocking for the iPhone 3G is not yet available.

UPDATE: Apparently, Installer is not available with this version of PwnageTool. » PwnageTool 2.0 released; Macs only. *UPDATED*