ZFS was the crown's jewel, no need to be "a fan" to recognize the technical merit behind it. Independently of the platform ... ZFS runs on IllumOS, FreeBSD and OS X ... haiku is implementing it afaik, too.
So it's just funny when you say "Solaris fan" when you see all those platforms, please, educate yourself → http://en.wikipedia.org/wiki/ZFS#Platforms
And ... ┐have you read the license? if not, please do (THE LICENSE, not the GNU's stance on the license, make your own interpretations, even the purists recognize the license as "copyleft", "per file copyleft" some people might say ... the "dont use it because allows linking with propietary software" argument that GNU's made is ridiculous when you ask yourself WHY does LGPL exists in the first place)
BTW btrfs was started by Oracle who also owns ZFS now.
ZFS is still evolving on its own, WITHOUT Oracle ... with a community behind it, in fact, implementations started to diverge from ZFS v29-31 and now, differences got deeper with the add of this: http://www.youtube.com/watch?v=REzvy59jQnw
Again, educate yourself → http://www.youtube.com/watch?v=-zRN7XLCRhc