zfSnap was developed on FreeBSD, therefore zfSnap works best on FreeBSD :)
http://www.freshports.org/sysutils/zfsnap/
There are plans to make a NetBSD port for zfSnap, but probably not until NetBSD officially supports zfs.
zfSnap was reported to work on Ubuntu Server 11.10 64-Bit
Starting with zfSnap v1.10.0 tested to work out of the box on:
zfSnap v1.10.0 was tested to work on Solaris 10, but GNU tools (grep, sed, date, ...) must be installed and PATH environment set in such way, that GNU tools would be used instead of Solaris 10 default tools.
Also you need to patch zfSnap #!/bin/sh to #!/bin/ksh or #!/usr/local/bin/bash (or wherever bash 4 or newer is installed. Bash 3 won't work)
There are absolutely no plans to make zfSnap work with Solaris 10 native tools. These tools are way too crappy, to say the least. Modifying zfSnap to work with them, would make zfSnap even more harder to read.
zfSnap v1.10.0 was tested to work on OpenSolaris 2009.06, but you must make sure, that PATH environment is set in such way, that GNU tools (grep, sed, date, ...) are used, instead of native tools.