Aside from BP-rewrite, encryption is probably the most awaited ZFS feature, but there have been sparse information regarding the status of both projects for about a year.
The ZFS crypto project which are going to deliver on-disk encryption for ZFS have now at least showed a small life sign. This is after a long time of radio silence from Darren, Sun and Oracle regarding the ZFS crypto project since May last year when "PSARC/2009/443 ZFS Crypto Updates" was published. Now there are references to a new PSARC, but it's not public so we have only the name to to look at: PSARC/2010/329 ZFS Crypto additional keysource types.
The last crypto releated PSARC from laste year, which was public:
PSARC/2009/443 ZFS Crypto Updates
From Prometheus to Sisyphus
6 months ago