Because Sun unfortunately chose to create a new and GPL incompatible license for “Open” Solaris it is not legally possible to directly port their interesting ZFS filesystem code into the Linux kernel, so any Linux kernel implementation would need to be a clean room rewrite under a GPL compatible license.
However, there is a way around this license incompatibility problem for filesystems by using the Linux Filesystem in UserSpace (FUSE) project. It (as the name implies) allows a filesystem to run in user space rather than in the kernel, a system now used by many other filesystem projects as an easy way of providing a filesystem paradigm for all sorts of wacky ideas (including filesystem access to Wikipedia through WikipediaFS).
I’m very pleased to announce that, thanks to Google, Linux will (hopefully) have a working ZFS implementation by August 21st, 2006.
Good luck to him – I’ve had a demo of ZFS on Alec’s laptop and it looked quite snazzy – it’s kind of a fusion of an online resizeable filesystem & logical volume manager.