Comment 3 for bug 827197

It does indeed appear that ecryptfs has moved itself back to being a module:

    -rw-r--r-- root/root 189368 2011-08-13 02:31 ./lib/modules/3.0.0-8-generic/kernel/fs/ecryptfs/ecryptfs.ko

despite the config:

    debian.master/config/config.common.ubuntu:CONFIG_ECRYPT_FS

And indeed on the machine:

    $ grep ECRYPT_FS /boot/config-`uname -r`
    CONFIG_ECRYPT_FS=m

Looking at the configuration options this is because ECRYPTFS is now dependant on ENCRYPTED_KEYS which is =m which drags ECRYPTSFS down to =m.

Pushed patches to fix this up to Oneiric.