The few lucky ones that are still stuck with A4 chip inside of their iPhone 4, iPad and iPod touch 4th generation just got the tethered jailbreak. The latest version of Redsn0w can jailbreak your phone but only in tethered mode, which means that the jailbreak will be gone after each restart but with a few mouse clicks you can have it back again.
Another bad thing about current Redsn0w is that it doesn’t install Cydia by default, meaning it will take some additional time to get this alternative store running, but then again, if you know how to jailbreak you should be ok to install Cydia and add a source.
We are sure that there will soon be a better version of Redsn0w that can at least get Cydia automatically and hopefully even bring the untethered jailbreak to these devices. We don’t have any idea when to expect iPhone 4S or a iPhone 5 jailbreak, as the new phones usually take more time to jailbreak.
If you are still convinced that going after this jailbreak is something you need to do, you can find detailed instructions here.