Please follow the steps below to jailbreak your iphone using Limera1n. This works for Iphone 3gs and Iphone 4. This Jailbreak also helps remove phones which are stuck on Emergency Call only.
Supported Models: Iphone 3gs and Iphone 4
Supported iOS versions: 4.0, 4.0.1, 4.0.2, and 4.1.
Download Limera1n here
Run limera1n.exe that you just downloaded
Click the make it ra1n button
iPhone will now enter recovery mode.
Now Hold the home buttons and power buttons
Release the power button
Iphone will now enter in DFU mode
An Image of Green raindrop will appear on your iphone as the phone is jailbroken.
The software will give an DONE output.
And the phone will be back ON. You will see and Green raindrop Limera1n Icon. Open it and you will see and option to Install Cydia. Install Cydia and Now your phone is Jailbroken.
If you need to Carrier Unlock your Iphone you need to install Ultrasn0w using the tutorial here.
If you need to Remove the Limera1n Icon from iphone please follow this tutorial.