Some notes on RootOnZFS article in wiki

[Mel Flynn]

Scot,

one last thing. I'm not sure if it's worth mentioning in the wiki, but I 
figured I'd put it out there.
If you follow the usr/ports tree with distfiles and packages as different zfs 
mounts, a nullfs exported /usr/ports tree will no longer contain these two 
directories as they are different filesystems.
That'll be a little gotcha, once you start your jails with shared ports tree.

(In my case, I went from a gmirror'd 7.2 to ZFS'd 8.0 and restored configs, 
home and jails from backup).
-- 
Mel