ZFS with a good storage oriented GUI...
ZFS with a good storage oriented GUI already exists, in the Sun Open Storage line.
With features like snapshot & cloning already solid - dedup is not much more sophisticated.
Dedup with Zones, LDom's, and xVM is a huge bonus! With Virtual Box or Thin Clients like the Sun Ray - the benefits are astounding to businesses!
Run 100 virtual servers or 100 virtual desktops on a server, served by a de-duped ZFS filesystem, and the common binaries would easily fit in a very small memory footprint since only one copy of each commonly used file would need to be in memory.
Dedup with clustering would be absolutely phenomenal!!! (We have to wait a little while longer for this one until Lustre source code is sufficiently leveraged...)
