In order to use the VirtualBox Guest Utils in the USB-Stick, when the USB-Stick is booted in a VirtualBox, you will need to do the following two steps by hand:
sudo apt-get install linux-headers-2.6.32-21-generic
sudo /etc/init.d/virtualbox-ose-guest-utils start
This bug is caused because of two different kernel's used during creation of the ISO image.