DISCLAIMER: This post is made merely for educational purposes. Follow this jailbreak guide at your own risk. Keep in mind that improper jailbreak procedure can brick your iPod Touch and that this post is made by human hands and as such, subject to imperfections. I suggest you consult other LimeRa1n jailbreak guides for Apple iPod Touch 4G before proceeding.
Reports have reached us stating that some LimeRa1n jailbroken iDevices are missing Calendar, Maps, Game Center and App Store icons and never regained them even after a restore. Be extra careful.
Here's how to jailbreak iPod Touch 4G running iOS 4.1 using GeoHot's LimeRa1n --
1. Get a Windows PC.
2. Download LimeRa1n for iPod Touch 4G on your PC via this link.
3. Connect your iPod Touch 4G with iOS 4.1 to your PC via USB
4. Click on LimeRa1n icon on your computer. This will sniff out your USB-connected iPod Touch 4G.
5. Click on 'Make It Rain' banner. This will prompt your iPod Touch to enter into DFU mode.
6. To enter into DFU mode, just follow the instructions on LimeRa1n window;
a. Hold down both Power and Home buttons (don't mind iTunes) until LimeRa1n tells you to release the Power button.
b. Doing this will make your iPod Touch 4G enter DFU mode
c. Once LimeRa1n flashes 'Expoiting...' note, let go of the Power button. You will then see LimeRa1n's logo on your iPod Touch's screen.
d. A message will pop up saying that the jailbreak is done.
7. Turn your iPod Touch back on.
8. Click on LimeRa1n app icon - white rounded square - on your iPod Touch. In LimeRa1n, tick Cydia, then click 'Install'.
That's it! Enjoy your jailbroken iPod Touch!