With the Advent of 10G Network Adapters…
I think it actually makes a lot of sense to build a diskless multimedia desktop now. One NFS server hidden somewhere in the garage, then a desktop that has a silent power supply and cooling system (read: Zalman), and the computer will emit zero noise! Perfect for watching movies, listening to/producing music and stuff. And it will automatically centralize daily backups too!
The trick would be to find a cheap gigabit switch with at least one 10G port.
And sure, you can use mirrors, or parity striping, but I wouldn't be surprised if you hit a bottleneck elsewhere.
Don't forget latency is still an issue, too!
Yes, latency is another issue, but it usually doesn't make that much of a difference, especially if frequently accessed databases (such as /etc/{passwd,group} and friends) are centralized onto the file server and clients refer to them over LDAP, NIS+ or some other means.
And latency I mean in the context of braindead software that insists on making blocking file accesses all the time. Like, say, CIFS. ;)