Good PDF overview slides here: http://www.opensolaris.org/os/community/zfs/docs/zfs_last.pdf
RAID comments in here: http://www.opensolaris.org/os/community/zfs/whatis/
Disk access / filesystem performance is the greatest bottleneck in PC performance (disk = slowest component). ZFS could make Linux go mach speed. And rid us of fsck forever.
ZFS needs to be kernel. FUSE is user space, a big performance hit. The release of ZFS is huge (in light of point above). The kerneldevs should get ZFS into Linux, whether it means (a) lobbying Sun for GPL, or (b) configuring Linux to allow separately compiled fs stuff (similar to the nvidia drivers). If anything ever argued for bending the "Linux house rules," ZFS is it. One of the few things that makes me want to customize my own Linux kernel. Talk to any Linux sysadmin who moved (down) from Solaris filesystem to Linux filesystems and you'll get an earful about ZFS.
M