Linux – ZFS on Linux based systems

Have you considered NexentaStor or Nexenta core? It's actively developed now that the OpenSolaris project's fate is unknown. Nexenta is also more GNU-like. The Nexenta Community edition is a good appliance-like implementation which leverages ZFS features and provides an excellent GUI. The Nexenta core is a stripped-down variant that's essentially a more usable OpenSolaris.

See: http://nexenta.org/projects/site/wiki/WhyNexenta

As far as I know, really the only option you have that approaches being somewhat reliable is to get a SAN that implements storage virtualization and connect your windows servers to it via iSCSI/FC/FCoE/etc.

The SAN will be able to give you similar features as ZFS does: snapshots, dynamic volume sizing, cloning, etc.