More conversations about Hammer capabilites has been going on, on the kernel@ mailing lists, including where Matthew Dillon describes where Hammer’s mirroring concept came from, and the possibilities of growing and shrinking filesystems. (Read to the end.) Also, he’s put up a preliminary paper describing Hammer – what it does, how to use it, and future plans. There’s a section on porting for those who might be interested.
KernelTrap’s still tracking progress, too.
(Apparently Hammer does not need to be in all caps as I’ve been writing it, going by the paper.)