Firstoff, to clear things up, unlike Apple or Android phones, there is no need to extensively "jailbreak" the Palm Pre/Pixi due to palm's ease with consumers using 3rd party applications. As most of you know, jailbreaking is simply gaining root acess within the phones operating system. Palm made this easy. To do so simply type:
webos20090606
this will bring up the search screen as you type, leaving you with the option "Developer Mode Enabler". By selecting the application, and selecting for the option to be turned on, you have "jailbroke" your phone. For windows users, from here install "WebOS Quick Install" using this palm supported application you can now self install homebrew applications, themes, and patches allowing you to easily take full use of your phone.
Of course, there are some things the application will not allow you to do, such as change operating system text, such as the carrier banner at the top left of the screen. These various, and often more risky tasks are done by editing and splicing code within the phones operating sytem.
Some good sites to continue with:
http://www.precentral.net/getting-started-homebrew-apps-patches-and-themes-webos-quick-installhttp://www.palmprehomebrew.comhttp://www.palminfocenter.com