So today I was messing about with metasplot+nessus and needed a confirmed target to check out, and found metasploitable - trouble is its only available as a VDK for vmware
the following can be used to convert it
sudo aptitude install qemu
qemu-img convert /tmp/Metasploitable/metasploitable.vmdk metasploitable.bin
VBoxManage convertdd metasploitable.bin metasploitable.vdi
and your done!