On N900: apt-get install unfs3

On Ubuntu PC: apt-get install nfs-common

On N900, edit /etc/exports and add this line:
/ 192.168.5.11(rw,no_root_squash)

(note: change the "allowed IP address" field with your Ubuntu IP address, use "rw" for read/write or "ro" for read-only)

On N900, start the daemon:
/etc/init.d/unfs3 start

On Ubuntu PC, you can now mount the root directory on the IP address of the N900 (change the IP accordingly):
sudo mount.nfs 192.168.5.7:/ /mnt
ls -al /mnt/home/user/MyDocs/DCIM

And pronto! -it works.


Note: my N900 and my Ubuntu PC both use fixed IP addresses (that "192.168.5.7" is my N900 fixed address).