It's easy to get USB support working in Kubuntu. Credit goes to David Grant for graciously posting the instructions on his blog at http://www.davidgrant.ca/virtualbox_usb_windows_xp_guest_ubuntu_hardy

Here's a summary of what you need to do:
1) Use the closed-source version of VirtualBox. Download it directly from Sun, do not use the version in the Ubuntu repositories.
2) Find out what the vbox users group id is with the command grep vbox /etc/group
3) Set up the /proc/bus/usb interface by adding the following lines to /etc/init.d/mountkernfs.sh (after the section where /proc is mounted). Replace with the group id you found in step 2:
#for hardy:
domount usbfs usbdevfs /proc/bus/usb -onoexec,nosuid,nodev,devgid=,devmode=664
#for intrepid:
domount usbfs "" /proc/bus/usb usbdevfs -onoexec,nosuid,nodev,devgid=,devmode=664

The author's point was that he could get a signed cert the says mozilla.org.

But if the author doesn't own the domain mozilla.org, the user is still going to get a warning in their browser about the domain mismatch between the cert and the domain visited. How is this any more dangerous than a regular self-signed cert? In this case the evildoer still doesn't control the domain, even though he or she has a renegade cert for it.