Filesystems Quo Vadis: Clients

Probably it's just a question of me not paying enough attention to the news... So: pointers welcome.

There are quie a few shiny new filesystems for local storage, like btrfs or HAMMER (and nilfs, Tux3, ext4, Reiser4...)

It seems the distributed storage side is covered as well, with ceph being merged recently. There are other systems (like, for example, Lustre), but they haven't appeared much in the news channels I tend to read. What I'd be curious is if any of these support hierarchical storage architectures like pushing out rarely used data to tape libraries. (But this is just idle speculation, I don't need this anywhere.)

But what I would really need is a replacement for NFS (v3): a classical client-server filesystem. I'm not sure NFSv4 is the “right” solution (where I'd use it, I currently can't because we rely too much on POSIX ACLs there, making the transition to NFSv4 quite a chore.) I think POHMELFS might be a solution in the long term, or CRFS, but I'm not sure how much progress there is on these; apt-cache search is silent, not a good sign. There's Samba 4 — I guess I'll have to look at it, since it's supposed to be much cleaner and nicer to use than its predecessors and might be a good solution even if no Microsoft systems are involved. Is this what small environments (a fileserver and 100 clients or so) will want to use? Comments are very welcome.