I'm assuming that this is place to report bugs.  If it isn't, then
please point me in the right direction and I'll submit it there.

The problem: On a clean install of Ubuntu Server 10.04 LTS with only
OpenSSH and Samba installed using the default repositories with
ppa:dajhorn/zfs added, apt-get install ubuntu-zfs fails to install
properly.  The compile for zfs-dkms fails.  The failure is such that
the overall install does not stop and that ubuntu-zfs gets reported as
installed.  However, the zfs.ko module is neither built nor installed.

Workaround:  apt-get remove ubuntu-zfs zfs-dkms spl-dkms dkms and then
apt-get install dkms and subsequently apt-get install ubunu-zfs.
Everything compiles and installs properly.  Issue the command zfs and
the modules are loaded and you are ready to go.

How to replicate the error:

1.  Install Ubuntu Server 10.04 LTS from the iso image.
2.  Take all defaults except for additional software, select OpenSSH
and Samba to be added
3.  After install is complete and the server is rebooted, apt-get
update
4.  apt-get install python-software-properties
5.  add-apt-repository ppa:dajhorn/zfs
6.  apt-get update
7.  apt-get install ubuntu-zfs

There isn't much text to offer, but here it is:

 * dkms: running auto installation service for kernel 2.6.32-32-
generic
 *      zfs (0.6.0.19)...   [fail]
 *      spl (0.6.0.19)...   [OK}

I'll be happy to generate a built transcript for you it you can tell
me how to do it.  I looked through /var/lib/dkms after the build for a
build.log but didn't find one.  I'm experienced with *nix and other
distros of Linux, but I don't have a lot of time on Debian/Ubuntu.  So
point me and I'm happy to help.

DKMS lacks the notion of a module dependency, so zfs-dkms Pre-Depends on
spl-dkms instead.  This usually gets the desired result, but it
occasionally fails like you report.