Well, if you're data-paranoid, like me, you can set your ZFS filesystem to keep 2 copies of every file on different parts of the disk. Then if your single disk has a sector or two go kaput, ZFS will notice the bad CRC on read and get the other copy.

I've also heard of other improvements for single-disk, and SSD specifically, but alas, I can't find citations right now.

Time Machine really stole the thunder on this for regular users.

Time Machine's "snapshots" suck. Entirely new file every time a bit changes? Really? My 500 gig external disk just filled up. And it's only backing up a 250 GB drive. And I only started using Time Machine a few months ago. Virtual machines & TrueCrypt volumes that change often are a royal pain with TM. ZFS, on the other hand, can store 4 months worth of backups of a 1TB RAID array on my fileserver in way south of a gig.

Also, ZFS send and ZFS recv are awesome ways to stream a filesystem snapshot over a network to, say, a Time Capsule. If you were so inclined.