iPhone Dev Team has released Redsn0w 0.9.8b1 to jailbreak on iPod Touch, iPhone and iPad running on iOS 5. iOS 5 Beta was Published in June only a few days back at WWDC. Jailbreak is connected only to now. Unfortunately, it only works with Mac, Windows version will be released soon, You can find the Windows Version here.
Download RedSn0w 0.9.8B1 For Mac
You can follow here to step by step jail break your iPhone 4 & 3GS, iPod Touch and iPad.