If you Google, there are many people offering many suggestion, some working for few people and some not.
Well, I tried the same in Intrepid Ibex Ubuntu Linux, but none of the suggestion worked for me.
So the most simple thing that I did and worked was read the manual and found there are two version of Virtual Box.
You can see the differences between them by going to http://www.virtualbox.org/wiki/Editions
Don't do anything with /etc/udev/rules.d/40-permissions.rules, /etc/init.d/mountdevsubfs.sh or /etc/fstab.
deb http://download.virtualbox.org/virtualbox/debian intrepid non-free" to it.
Also I recommend you to add VirtualBox GPG key.
Then update by typing, "sudo aptitude update"
Remove old virtual box if you have installed by "sudo aptitude remove
virtualbox-ose"The setup will ask you to add yourself or the VirtualBox user to vboxusers group, do so.
Install newer virtual box by "sudo aptitude install virtualbox-2.1"
Run virtual box and you should see USB settings.