Sage Weil has posted on this. Ceph is distributed file system, with an MDS, and a few other things, that looks quite interesting. Not necessarily on the high performance side, but on the simple object storage side. The client going in to 2.6.33 could be quite interesting.
Pay attention to Ceph. Think of Lustre, without the nasty kernel requirements on server and client, and with in-kernel support. Including Ceph within the kernel (the second! recent distributed file system to make it in) begs the question about potential longevity of other similar projects.
This is a good thing. Competition for minds and users.