Targeting the developers of jailbroken apps – Redsn0w beta has now been released by the iPhone dev team! With the methodological use of older exploits, these awesome guys have unexpectedly come up with jail breaking guide for the iPhone 4.0 OS, although this works on the Apple iPhone 3G only.
It’s indeed quite surprising to note that this iPhone jailbreaking for 4.0 was released without the mention of releasing iphone 3.1.3 jailbreak, perhaps the dev teams are clinged with the latest iPhone 4.0 OS and prefer it that way.
In anyway, here is the guide to jailbreak iPhone 4.0 with Redsn0w 0.9.5 on your Apple iPhone 3g (Repeat: Not for iPhone 3GS). Thanks to Taimur from Redmondpie, Sandip from Blogsdna, and of course, the dev wiki for compiling a proper iphone jailbreak guide.
Read this carefully: As a remainder, this jailbreaking works only for iPhone 3G which has 4.0beta1 IPSW installed. You need to be on the Mac OS X running the latest iTunes version since jailbreak apps are developed on this platform.
You also require a registered Apple UDID to activate/unlock your iPhone. Use this for testing and educational purposes only. And finally, other iPhone firmwares cannot be unlocked! Strictly for iPhone 4.0 (Stressed this enough number of times to make sure you are aware of your doings) 
