blackra1n is the latest, simplest Jailbreak tool from iPhone hacker George Hotz (Geohot) and supports all modern iPhone and iPod touch devices running the latest 3.1.2 firmware. blacksn0w is the associated Unlock utility. (Jailbreaking lets you run software not approved by Apple, like background tasks, Google Voice apps, etc. Unlocking lets you use your iPhone on other carriers, like T-Mobile US or international carriers when traveling). blackra1n makes the process faster and easier than ever before, but if you need extra help, TiPb has your back.
Note: For those of you who are planning on jailbreaking your new iPhone 3GS with the updated bootrom, you should be aware that BlackRa1n supports only a tethered jailbreak