In past before every major iOS release we have provided our analysis on jailbreak & unlock scenarios but this time we left out iOS 5, the reason behind is Limera1n bootrom exploit which was found by GeoHot. As the Limera1in is bootrom exploit it can’t be fixed without changing hardware. But Apple can always fix the kernel hack used to make jailbreak untethered and this will be likely case of iOS 5 too.
So if you are curious to know about iOS 5 jailbreak then answer is yes. iPhone4, iPhone 3GS, iPod Touch 4G, iPod Touch 3G & iPad 1 can jailbreaked on iOS 5 but it may be tethered jailbreak meaning you have to connect to PC or Mac every time you reboot your iOS device.
As a proof Musclenerd has also posted screenshot of jailbroken iPod Touch 4G running iOS 5 Beta using Limera1n and tethered boot. Screenshots after the break,