From a conceptual standpoint, I love NAS [network attached storage] virtualization and file area networks (FAN...
But it's not just a question of NAS -- we need greater levels of virtualization throughout all of our storage infrastructure. What I like about these two concepts is that they give you a higher level of intelligence, ease of management and higher utilization of the physical storage.
What FAN does is 'network the networked storage' so that you have common communication between storage devices. This allows users to move data between systems for load balancing or tiering. I can replicate heterogeneously. I can create a federated storage view of all storage systems to improve access and management. The power comes when using storage devices in concert with one another.
These are new concepts in an emerging area of technology, but this is where storage networking is headed.
Check out the entire NAS FAQ guide.