iJailBreak is an automated jailbreaker for your iPod Touch licensed under the GNU General Public License v2 written by 13-year-old AriX. The only user interaction required is for you to restart the iPod Touch. Works on Macintel OS X Tiger. PPC version is in the works.
You can discuss iJailBreak at the Apple-Touch forums.
iJailBreak is heavily dependent on Niacin and Dre's awesome tiff hack, you can find them at toc2rta.com. They really started the whole iPod Touch hacking scene. iJailBreak also makes heavy use of iPhuc, which you can find on Google Code.