it looks like they put a key/value store in the kernel and they came up with a new userspace API for it. i can see also see how getting something like this into the mainline kernel is going to be a big uphill battle, but it might actually be a really big win.
"most ambitious storage project undertaken since ZFS" (http://www.acunu.com/2011/03/why-is-acunu-in-kernel/)
it looks like they put a key/value store in the kernel and they came up with a new userspace API for it. i can see also see how getting something like this into the mainline kernel is going to be a big uphill battle, but it might actually be a really big win.