Every day good news from Sun.
Not only, that the Sun C / C++ compilers and Sun Studio 11 are now available for free, Solaris Express Build 27 including the new integrated Filesystem and Volume Manager called ZFS is available for download now. Start using ZFS reading the ZFS Intro Page and the zfs(1) man page.
Not enough?
Here’s a nice Sun ZFS presentation and the full Solaris ZFS Administration Guide.