I managed to boot Debian on an 860 using svs57's guide. My SD card was originally formatted as ext2, and Debian didn't like that, so I created a journal on it to make it an ext3-type. Debian booted OK after that.
I couldn't find loadkeys anywhere, so do I need to copy it over from Angstrom or something? It's not very usable when I can't type '/'!
I installed the Angstrom X server, but it couldn't find a touch screen library or something, so I guess I will need to install Debian xorg or something to get that to work.
BTW I have streamlined flashing of the kernel by using some backup and restore scripts which I found somewhere - can't remember unfortunately, but they are called backup.sh and restore.sh. The backup script creates files boot.pdx, emerg.pdx, kernel.pdx, root.pdx, which I have on a CF card. To jump between pdaXrom and Debian kernels, I simply use
restore.sh -e -r -u -s /mnt/cf/backup
after renaming the relevant kernel to kernel.pdx, and putting it in /mnt/cf/backup. I've copied the scripts to the CF card so I can run this script from the uboot emergency screen, or directly from pdaXrom.
If no-one can find the scripts, I'll post them here. Apologies to the author for not remembering where I found them!
Dan