According to Only Ubuntu, to enable auto-mounting of internal drives on bootup, edit the file /etc/hal/fdi/policy/preferences.fdi
and change the line
<merge key="storage.automount_enabled_hint" type="bool">false</merge>
to this:
<merge key="storage.automount_enabled_hint" type="bool">true</merge>
From now on, internal drives should appear on your Desktop.