apt-get install ufsutils
mount -r -t ufs -o ufstype=ufs2,ro /dev/sdb2 /mnt/ufsdrive
The above is what I did to get a ufs partition mounted read-only (best I could get).
Now sure why I had to mount it only read-only or why it was the second partition (it was a fresh format on FreeNAS’es part) but yeah..
Here’s more: http://askubuntu.com/questions/85154/mount-ufs-filesystem