It seems people don't know what Quickpwn does. Quickpwn just jailbreaks and activates the iPhone. It doesn't install a completely new firmware like PwnageTool does. If you have an unlocked iPhone with 2.0.2 and update to 2.1 the unlock should stay. If you do a restore to 2.1 unlock might not survive and you have to wait for a new version of QuickPwn that works on firmware 2.1. Or downgrade to 2.0.2 and jailbreak it again.