There is a known problem between Ubuntu Lucid as host OS and Virtualbox 3.2 when it comes to USB devices. Everything works fine except the USB controller — the devices show up greyed out in the guest OS.
If you have the same symptoms, it is likely a permission problem. Check that your user is a member of the “vboxusers” group.
You can do this through the GUI: System > Administration > “Users and Groups”. Click on “Manage Groups”, scroll down to “vboxusers” and check if your user is listed. If not, add it. :-)
You can also check from the command line:
groups $USER
If “vboxusers” is not in the output, add your user to the group with:
sudo usermod -aG vboxusers $USER
You will need to log out and back in for the group change to take effect. In some cases a full restart is required.
That is it.