Whenever I install XBMC, one of the first settings I change is I enable auto mounting of drives. It's a relatively simple change, but requires you modify a file on the filesystem.
For Ubuntu Lucid 10.04:
I've noticed that it's not necessary to manually remove the nodiskmount option on 10.04 (grub2). The modifications that I used to make in /boot/grub/menu.lst on Ubuntu Karmic, I now have to make in /etc/default/grub on Ubuntu Lucid.. When I removed the nodiskmount on Ubuntu Lucid I started having some issues with the disks being mounted in odd ways (eg. my NTFS drive being mounted directly to /media). What I found is that instead of removing nodiskmount, if I just properly labeled my partitions, they would automatically show up properly -- you can label your partitions using the e2label command.
As I noted in the comments below, you may still need to remove nodiskmount in Ubuntu Lucid to get your eSATA drive to mount (especially true for people who followed my Revo 1600 guide). What I found is that because the internal drive on the Revo 1600 is NTFS, it will cause the weird issues I mentioned above. If you happen to fall into this case, I would highly recommend you check out my article on Drives Being Mounted with Odd IDs. The article explains how to find the unique identifier (UUID) for your drive and manually create an FSTAB entry to mount your drive with your specifications each time the system loads. Now that I've wrapped my head around how FSTAB works, I prefer to use this method as it lets me set my own unique name, path, and other settings for how the drive is mounted.
However, if you'd still like to modify the grub parameters for other reasons, I've included the details below...
Open the file /etc/default/grub:
sudo nano /etc/default/grub
Find the line for loading your system (usually starts with GRUB_CMDLINE_LINUXDEFAULT) and make sure it's not the commented out line that often comes default at the top of the file. Modify this line so it no longer has the nodiskmount option in it.
Save the file and close it. Ctrl+O, Enter, Ctrl+X.
Run the following line to update grub and then reboot:
sudo update-grub sudo reboot
For Ubuntu Karmic:
If you are still booting from the XBMC-Live 9.11 Camelot USB stick directly, this will be in the syslinux.cfg file. If you have installed XBMC to disk, this is in the /boot/grub/menu.lst file.
To remove this flag from the menu.lst file, telnet into the XBMC machine (use the instructions from the sabnzbd install post if you don't know how), then open up the file with your favorite editor:
sudo nano /boot/grub/menu.lst (you may have to enter your root username and password -- typically xbmc / xbmc)
Arrow down to the first line under "## ## End Default Options ##" near the bottom of the file and on the "kernel" line arrow to the right until you see the "nodiskmount" text. Delete this text then press Ctrl+O [enter] to save the file then Ctrl+X to exit. Reboot your box and you should now see some new items in your file manager usually named something like sdb1 or sda1.