Windows users can now jailbreak iPhone 2G, 3G, 3GS 3.1.2 firmware! Thanks to George (GeoHot) for creating blackra1n. Using blackra1n you can easily jailbreak your iPhone. But iPhone 3G and 3GS users who don’t want to unlock their iPhones please don’t upgrade to 3.1.2 using iTunes as baseband will be updated and once it’s updated then it cannot be downgraded.
Here’s a detailed video tutorial that shows you how to jailbreak using blackra1n.
Firstly, update or restore the firmware to 3.1.2 by holding SHIFT + clicking Update or Restore on iTunes, and locate the .ipsw firmware file that you downloaded.
Next download and run blackra1n.exe. If you are using Windows 7 or Vista, run the app as admin– Right click and selecting Run as Administrator. Also make sure that you run in XP compatibility.
Once done click on make it ra1n. It will take about 1 minute, iPhone will reboot automatically once done.
That’s it! Your iPhone is now jailbroken. But, you need to do one more thing. You’ll find a new icon with the name blackra1n. Open blackra1n and select Cydia, Icy and install them. Once it’s installed the springboard will reboot. Voila! Your iPhone is now jailbroken fully! Reboot to make Cydia work properly.