I agree that the "stood still for decades" seems to be a bit of an
exagerration. During the 1990s journalling filesystems became commonplace,
as did btree structured directories. Netapp (aside from its proprietary
nature) has probably done more to date to advance the state of the art in
filesystems than anyone else has, due to perhaps a fifteen year head start
over ZFS. ZFS is so fundamentally different from WAFL that I don't know
how anyone could confuse them though.
Other than ZFS and perhaps Reiserfs, there does appear to have been a slow
period in filesystem development for about the past decade. It is great to
see that things have picked up.
What I am hoping to hear is that the BTRFS or possibly ZFS folks have
figured out how to support a write-in-place mode, so that the storage of
filesystems within filesystems as well as certain large databases does not
degrade excessively due to fragmentation issues.