Joanna and the crew over at Invisible Things have posted a tool to demonstrate how trivial it is to circumvent full-disk encryption products. Evil maid requires that you have access to the machine and can boot it using a usb-stick with the software installed. It then is able to transparently record the user's passphrase for the disk. This is another example of how full-disk encryption products need to be architected carefully to ensure that problems like this can be considered and controls put in place to avoid them.