I'm having the same problem.
I've been running ZFS on 12.10 for a few weeks with no issues, today I rebooted as apt had upgraded the kernel and now ZFS is broken.
This is the PPA I'm using: https://launchpad.net/~zfs-native/+archive/stable
Here's what I've tried so far:
$ uname -a
Linux Goon 3.5.0-21-generic #32-Ubuntu SMP Tue Dec 11 18:51:59 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
$ sudo zpool list
Failed to load ZFS module stack.
Load the module manually by running 'insmod <location>/zfs.ko' as root.
$ find /lib/modules -name zfs.ko
$ sudo insmod /lib/modules/3.5.0-19-generic/updates/dkms/zfs.ko
insmod: error inserting '/lib/modules/3.5.0-19-generic/updates/dkms/zfs.ko': -1 Unknown symbol in module
$ sudo modprobe zfs
FATAL: Module zfs not found.
Now it seems to me that the zfs.ko module should be in
$ sudo dmesg | grep zfs:
[ 1380.577459] zfs: Unknown symbol __taskq_destroy (err 0)
[ 1380.577472] zfs: Unknown symbol spl_cleanup (err 0)
[ 1380.577480] zfs: Unknown symbol nvpair_value_uint8 (err 0)
[ 1380.577487] zfs: Unknown symbol kmem_debugging (err 0)
[ 1380.577501] zfs: Unknown symbol vn_openat (err 0)
- this continues for hundreds of lines -
but I've no idea how to solve this.
Update: I've added the daily PPA and upgraded which seems to have solved the problem. Though I don't feel too comfortable using the unstable branch on my production filesystem, so still looking for solutions on this! I guess if it comes to it I'll just wait for stable to be updated again and switch back.