So yes, I have a root shell on the Kindle 2. No, I'm not going to post a step-by-step HOWTO. (See my post from earlier today if you're wondering why.)
My next step is the armel virtual machine to make cross-compilation a breeze.
If you're interested in voiding the warranty on your Kindle 2, my writeup about USB Networking, igorsk's posts from 2007, the Kindle 2.0.1 update, a copy of the right build of busybox and a little bit of hackery will get you your very own login on a cute little ARM Linux box with 128 megs of RAM.