KQ Infotech has been working on this native ZFS module that in turn is based on the work of the Lawrence Livermore National Laboratory. KQ Infotech has now announced their ZFS work with a few details on their Linux kernel module and to apply to be part of the beta testing process.
KQ Infotech is only letting 25 people beta test this module, so good luck getting in (we are in, but due to Oktoberfest and not being given this code earlier, we will not be testing it at this time). With their ZFS module being based upon an older Zpool version and other limitations of the port, some of the downfalls for this ZFS Linux implementation are no data de-duplication support, name normalization support, quotas, root-able file-system, access control lists (ACLs), remount, and KERN SMB support. ZFS commands of rollback, promote, userspace, groupspace, share, unshare, send, receive, allow, hold, and release are also unsupported at this time.
We have heard from KQ Infotech that, "one month down the line, we will put it for everyone." For those beta testing it in the interim, the ZFS module for Linux is currently distributed as Fedora packages for the Linux 2.6.31/2.6.32 kernels, Ubuntu 10.04 with the Linux 2.6.32 kernel, and Red Hat Enterprise Linux 6.0 with the Linux 2.6.32 kernel. No source is currently available besides the work done by LLNL. This ZFS implementation is also only supported on x86_64 Linux.