Jailbreak Your iPhone 3G or iPod touch 2G on iOS 4 Using redsn0w 0.9.5
Download redsn0w 0.9.5: http://wikee.iphwn.org/howto:rsbeta
In this video I show you how to jailbreak your iPhone 3G or iPod touch 2G running iOS 4 using redsn0w 0.9.5. Currently this is only recommended for advanced users but if you like you can jailbreak your device on iOS 4 today. You will need either a Windows or Mac computer and either an iPhone 3G or iPod touch 2G MB model (not a MC model) running the iOS 4 GM or Gold Master.
If you have everything you need then the jailbreak is quite simple especially if you've ever used redsn0w before. Simply follow the instructions in the video and you should be jailbroken in no time.