Here is a quote from someone involved in hacking the iPod Touch... see the last line. Many many people think that iPod Touch is far far more difficult to hack than iPhone, and the iPod touch firmware is coming to iPhone in the next firmware release.
http://www.tuaw.com/2007/09/20/ipod-touch-state-of-the-jailbreak/
"The iPod touch jailbreak attempts continue but there's little progress and less to report. Martyn, one of the hackers, has disassembled his touch and has attempted to read the chips directly. This hasn't been a huge success. I have been using iPhuc's grestore mode and my digital camera's video to try to see if we can learn more about the vocabulary the touch uses to communicate with iTunes. You can view my extremely blurry pictures in the attached gallery.
Does the touch indicates the future of the iPhone? The news looks bleaker by the day."