POHMELFS in the 2.6.30 kernel
While DST is a rather mature project and I do not expect it to change, POHMELFS will evolve into quite different entity.
To date it is a simple NFS-like filesystem with several features, namely the most interesting are local data and metadata writeback cache, ability to write to multiple servers and balance reading among them (you can find others on the homepage). This is really not a distributed filesystem, albeit a parallel one to some degree.
And reality says that no one really wants to change their existing NFS network to something new, even with higher performance, since the old systems already work and all their underwater stones were found.
Instead POHMELFS will evolve into the real distributed area with elliptics network, which will become its distributed hash table data storage. This is the main reason I will not ask to move POHMELFS from the staging tree for some time (at least in upcoming merge window) and will change it there.
Amount of features elliptics network provides is not really comparable with the existing old-school distributed systems, this is just a completely new and very different solution.
There is a number of potentially complex parts, but they are all solvable, so stay tuned for the new results!
EDITED TO ADD: Someone created a wikipedia article with spartan description :)