iPodXS

iPod 1G on 3.1.2
iPod 1G on 3.1.3
iPod 2G on 3.1.2
iPod 2G on 3.1.3
iPod 2G on 4.0
iPod 3G on 3.1.2
iPod 3G on 3.1.3
iPod 3G on 4.0
iPad on 3.2
iPad on 3.2.1
iPhone 3G on 3.1.2
iPhone 3G on 3.1.3
iPhone 3G on 4.0
iPhone 3G on 4.0.1
iPhone 3G[S] on 3.1.2
iPhone 3G[S] on 3.1.3
iPhone 3G[S] on 4.0
iPhone 3G[S] on 4.0.1
iPhone 4 on 4.0
iPhone 4 on 4.0.1

1) Start iTunes and backup everything from Contacts, Calendars, Photos, Videos and Apps.

2) Update your iDevice on the latest iOS 4.0 firmware with iTunes otherwise skip to step 4.

3) Once you are done with the update, make sure you are connected to a WiFi network.

4) Open Safari on your iDevice and navigate to http://jailbreakme.com.

5) “Slide to Jailbreak” to begin the jailbreak process.

6) Wait till the jailbreak tool download the required files..

7) Once the download is completed, it will automatically start the jailbreak process. Wait till the jailbreak process is completed.

8) Once done, you will be greeted with a message saying that the jailbreak is complete.

9) Close the browser and look for Cydia. You should now have it on your phone!

 

Alternatively GeoHot's Limera1n tool can be downloaded from here and used to jailbreak devices on Windows and Mac OS X.

Compatible devices are:

iPhone 4
iPhone 3GS
iPod Touch 4G/3G
iPad

Note: Greenpois0n can be run on Windows, Mac OS X and Linux. The listed devices must be running iOS 4.1

1) Start iTunes and backup everything from Contacts, Calendars, Photos, Videos and Apps.

2) Update your iDevice to iOS 4.1 firmware.

3) Download the appropriate version of greenpois0n from here.

4) Connect your iDevice via USB.

5) Open greenpois0n and click jailbreak.

6) Follow the on screen instructions.

7) The jailbreak will complete automatically and when done you will find an application called Loader on your homescreen

8) Open the Loader app and click on Cydia, then select the Install Cydia option.

9) Congratulations you are now jailbroken on iOS 4.1!