Proxmox 3.4 was recently released with additional integrated support for ZFS. More details are provided here in the Proxmox ZFS wiki section. I also decided to start gathering up another more current round of links related to performance, best practices, benchmarking, etc.
If you are looking for up to date links to help you understand some of the more advanced aspects and use cases surrounding zfs, or if you are just getting started and are looking for some relevant reading material on the subject, you should find these links extremely useful:
1.The state of ZFS on linux
2.Arch linux ZFS wiki page
3.Gentoo linux ZFS wiki page
4.ZFS Raidz Performance, Capacity and Integrity
6.KVM benchmarking using various filesystems
7.How to improve ZFS performance