I installed a copy of the ARMEL port of debian onto my BPDN. I found the instructions here: http://www.androidfanatic.com/community-forums.html?%20func=view&catid=9&id=1615
Basically you need to put an image of an EXT2 filesystem on your sdcard, then you copy some shell scripts to a different location where you can give them executable status. The shell scripts mount up the image via a loopback interface then give you a chroot'ed shell into the system. Now I'm usually a slackware guy, so I ran into some learning curve regarding the apt command. Everything was going fine until I accidentally overfilled the image. Then apt crashed and corrupted its database. Not cool. I eventually got it sorted, but do yourself a favor: figure out how much crap you are going to need first, then resize the image before you copy it to the machine and start doing the apt-get install game.
I put X11 and LXDE on there. Then I decided that the machine was way too slow, so I got jwm to use instead of ldxe. I also got tcl8.5-dev and tk8.5dev and xmahjongg, and emacs. Eventually I want to run whim as a window manager on it. The 128meg ram is a real limiting factor. I have not had such a slow linux box since I was running slack 3 and open look on a 486 with 128 megs of ram an a 1 gig drive back in 1996. I may end up swapping off the sdcard, which I suspect will kill it dead.