oh, totally missed this thread until today, thanks for pointing it in another thread
well, go on if it works for someone :-) I won't help much until I get the device.

My ideas about bootmenu for N900:

if it will live in rootfs I plan for it to be very initfs like i.e. self-contained. It should have its own busybox environment (statically linked and/or using uclibc) and live in its own place (/boot, /initfs, maybe even chrooted) so it will work even when someone thinks apt-get (dist-)upgrade with busybox removal and libc upgrade is a good idea.

Most of the time the breakage is either messing startup sequence later in the boot order or apt-get upgrade mess. 'rm -rf' moments or flash filesystem corruption is not so likely. And having it self-contained could help with putting it somewhere else too (own initfs partition if possible, built into kernel as initramfs). When based on N8x0 uclibc initfs environment we could also have same build of all the recovery tools embedded in bootmenu for N8x0 and N900.