So, Dave, if I may get philisophical...
There are two ways to make technology progress, neither is better...
1. Decouple something into layers to add freedom: An application that uses NFS over RPC over TCP over IP over Ethernet over copper.
2. Merge layers to add speed: Network Attached Storage marries the filesystem layer and the disk layer, and marries all that to the network.
NetApps do #2. SANs do #1.
--tal