I know it’s been a very long time since the site has been updated, but I figured I’d kick it in the pants for this guide on HeHe2.net for jailbreaking your G1. This guide will give you “root” access, which basically lets you do whatever you want to your phone, just like special developer’s G1 from Google allows.

[...] Before I start this howto, I must tell you that this hack doesn’t just give you multitouch, it actually opens up the possibilities wide open for you. You can change your theme, tether (use your phone as a wireless modem), auto-rotate, get a fully operable task manager…and much much more! So if you aren’t really interested in multitouch, this guide might also be of great value for you [...]

This will also allow you to install applications from other Linux distributions, such as the widely-used Debian. All the usual warnings apply when dealing with firmware changes. Happy hacking!