Geoh0t today released the first official jailbreak for ever iOS 4.1 device available. The best thing about this jailbreak is that Apple can’t fix this without a hardware update. So, if you now own an iPhone 4, it will be jailbreakable for the rest of your life :)

Here is what geoh0t wrote on his site:

limera1n, 6 months in the making
iPhone 3GS, iPod Touch 3G, iPad, iPhone 4, iPod Touch 4G
4.0-4.1 and beyond+++
limera1n is unpatchable
untethered thanks to jailbreakme star comex
released today to get chronicdev to do the right thing
brought to you by geohot
hacktivates
Mac coming soon
follow the instructions in the box, sadly limera1n isn’t one click
that’s the price of unpatchability
as usual, donations appreciated but not required
still in beta, pardon my ragged edges
AppleTV is technically supported, but theres no apps yet
zero pictures of my face

The limera1n jailbreak is currently only available on Windows, but a Mac version should be coming in the near future (you can use a virtualization software on you Mac until a Mac version is available).

Here is what you need to do, to jailbreak your iPhone 4 on iOS 4.1:

1. Download Limera1n for Windows, follow this link.
2. Connect your device via USB and hit the ‘make it ra1n’ button.
3. Wait for the device to enter recovery mode.
4. Hold Home + Power buttons until you see the “release power button” message in Limera1n.
5. Release the Power button when you see the text in Limera1n.
6. Wait while the device boots into DFU mode.
7. Limera1n does now the dirtywork, and injects itself in the bootrom of your phone.
8. The Jailbreak is done when your device is finished with booting
9. Now you can use the Limera1n.app on your iPhone to install Cydia (jailbreak app store).