Tweaks for ext4
a)install leafpad
open terminal and enter:
root
leafpad /etc/evend.d/rcS-late (search for ext3 and replace with ext4)
reboot
slide keyboard and enter to recovery-console and type:
tune2fs -m 0 /dev/mmcblk0p2 (removes the reserved space)
reboot to maemo
b)
copy mount-opts-overwrite to /etc/default/
copy fstab to /etc/
reboot and voila

files are in the archive atached to this post

A new life for n900 put ext4 plus ext4 tweaks + the other tweaks (hw of hildon , swap on sd , oc, decrease swapiness ,dsp oc plus codecs) and you have a new phone