We're currently in the "end game" for ZFS development - pushing full
speed towards integration (I won't make claims about an exact time
frame). We considered a more accessible beta program (as well as
opensolaris.org hosting), but it was not an efficient use of team
resources at this point in time, and would likely delay the eventual
integration into Nevada. We promise we're doing everything possible to
get ZFS putback ASAP.
So it looks like it's not that far in a future when ZFS will be publicly available. I can only add that you will really love its simplicity and features.