> Here's a video showing how to create an encrypted partition using the
> manual partitioning step in the installer. You probably did it wrong.
> Don't feel bad - I did it wrong three times before I got it right for
> the video, and I've done this before.
> http://distro.ibiblio.org/refracta/misc/partition_encrypt-4.ogv

Thanks for the video, it took me more than three attempts :P.
I had existing partitions on the drive that I needed to keep so did not
go near the 'use entire disk' option. The partitioning in the video does
not encrypt the entire disk, it leaves /boot outside. Kernel and initrd
are exposed giving a potential attack vector.