Christmas is here again, folks! The iOS 5 untethered jailbreak is now available for the A4-based iPhone, iPad and iPod using Redsn0w. There are a few steps, as usual, to get it working, but this untethered method is much easier than previous attempts, it's literally as easy as 1, 2, 3:
1. Download Redsn0w for Mac and Windows.
2. Run Redsn0w, click on "Jailbreak" and check "Install Cydia". Follow the instructions on the screen.
3. Wait and be done.
How easy is that! If you have an unlocked iPhone, you should choose the custom IPSW option to preserve it. As usual, these things can go wrong, so take your own responsibility for it. If it doesn't work, flashing back to the original Apple firmware isn't too hard. At the moment, this does not work with A5-powered devices such as the iPhone 4S and iPad 2.