JailbreakMe is the easiest way to free your device. Experience iOS as it could be, fully customizable, themeable, and with every tweak you could possibly imagine.
Jailbreakme supports the following devices and firmwares:
iPhone 2G, iPhone 3G, iPhone 3GS, iPhone 4, iPod Touch 1G, iPod Touch 2G, iPod Touch 3G, iPod Touch 4G, iPad 1 and iPad 2. iOS 3.1.2, 3.1.3, iOS 4.0, 4.0.1, 4.2.6, 4.2.8, 4.3.0, 4.3.1, 4.3.2, 4.3.3.
To jailbreak, simply visit jailbreakme.com from your device.