Blackra1n released by GeoHotz is the first official 3.x.x firmware jailbreak for Windows and Mac. It is also the first jailbreak for iPod touch 3rd Generation! This is quick one-click jailbreak. No need choose settings or go into DFU or Restore mode. Just plug it in and hit "Make it ra1n" on your computer.
Devices Supported: iPhone 2G, iPhone 3G, iPhone 3G [S], iPod touch 1st Gen, iPod touch 2nd Gen, and iPod touch 3rd Gen
Computer Supported: Windows and Mac
Firmware Supported: 3.1.2, 3.1.1, 3.1.0, and 3.0
Necessary Downloads: Blackra1n and IPSW for your device file
Exceptions: If your iPhone is unlocked (does not use an official carrier), do not jailbreak. iPod touch 3rd Gen is a tethered (what does that mean?) jailbreak.
To find you IPSW file, go here.
On the second drop-down bar, find your firmware file that matches with your device. Refer to the examples below.
iPhone 2G- Find iPhone 2G (3.1.2/7D11)
iPhone 3G- Find iPhone 3G (3.1.2/7D11)
iPhone 3G[S]- Find iPhone 3G S (3.1.2/7D11)
iPod touch 1st Gen- Find iPhone 1G (3.1.2/7D11)
iPod touch 2ns Gen- Find iPod touch 2G (3.1.2/7D11)
iPod touch 3rd Gen- Find iPod touch 3G (3.1.2/7D11)
How to Jailbreak
If you are having problems, you may want to wait for the Dev Team's Redsn0w jailbreak but that is coming in an unknown amount of time.