- Snapshots. This feature was the reason people originally thought it was behind Time Machine.
“A snapshot is a read-only point-in-time copy of a filesystem which takes practically no time to create and uses no additional space at the beginning. Any snapshot can be cloned to make a read-write filesystem and any snapshot of a filesystem can be restored to the original filesystem to return to the previous state.”
Because this is implemented on the fs level, it's very fast and totally transparent.
- Dynamic striping. ZFS not only promises much improved consistency, but also performance. Dynamic striping allows to write to all devices in a “pool” simultaniously.
Boot support is not actually implemented in the FS. Because it's such a low-level thing, it has to be implemented in the actual hardware (ROM). This is definitely something that will set the PPC and Intel Macs apart one day since the Intel machines have EFI which is a modern programmable BIOS that Apple will probably one day update to support booting from ZFS.