For those unfamiliar with Debian GNU/kFreeBSD, it takes the GNU user-land but runs it atop the FreeBSD kernel rather than Debian GNU/Linux with the Linux kernel. You can still use apt-get and do most anything you would with the Linux-based Debian distribution (aside from different hardware compatibility and other support differences), but instead you're running the FreeBSD kernel.
While the upstream FreeBSD project doesn't have an easy root ZFS file-system installation option within FreeBSD 8.0/8.1, this isn't particularly ground-breaking, as the FreeBSD-based PC-BSD already has ZFS installation support that is quite easy to work.
This ZFS installer support to the Debian GNU/kFreeBSD distribution also has no impact on Debian GNU/Linux ZFS support as there cannot be any upstream ZFS Linux support at the moment due to license incompatibilities between the CDDL-based Sun/Oracle ZFS and the GPLv2 Linux kernel. There is the new native ZFS Linux module that we have talked about at length and benchmarked, but it's living independently of the Linux kernel tree due to the license issues and being developed by KQ Infotech and Lawrence Livermore National Laboratory. This will likely not find its way into Debian GNU/Linux (or most other distributions) in any form in the foreseeable future.
For those interested, we do have Debian GNU/kFreeBSD benchmarks from this October as well as additional comparisons this summer comparing Debian GNU/Linux and Debian GNU/kFreeBSD. The announcement of ZFS installation support in Debian 6.0 Squeeze can be found in this blog post.